Isn't that what the commenter you're replying to was talking about? There is no restriction against drafting, but Lael still imposed a restriction on herself against it. Pretty impressive!
Drafting would be allowed for a team effort, which would be multiple cyclists.
I don't understand therefore why you write: "There is no restriction against drafting"
Lael has imposed additional restrictions on herself in previous races in response to criticisms. This is not an example of that.
FWIW, the solo self supported record is viewed as the most challenging bikebacking/touring achievement - and around the world the longest. It is amazing
(1) Wikipedia lists as one of the rules to not draft. That is the 5 bicycle length minimum distance provision [2].
(2) think of fastest-known-times (FKTs) like sailing around the world. Guiness does not list them all, guiness is not the authority of them. Some FKTs are well known, others are niche. Like how fast to race down your neighborhood street could have a FKT and you could be the holder of it. The authority is potentially just the local community. For bikepacking, there is not one single authority like Guiness. FWIW, trackleaders.com [3] is a pretty well known tracker for bicycle FKTs. For most races, the race organizer might keep track of the FKTs by year and overall FKTs.
(3) bikepacking is somewhat underground. There is essentially no money in it, there is low formality. There are only a half dozen or so professional bikepackers total, in the world [source: to my knowledge and recollection of GCN stating exactly that]
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Longer, more detailed response: Bikepacking (aka bicycle touring) is somewhat underground. The offroad crown jewel race for bikepacking and self supported is often considered the Tour Divide (TD). The equivalent big paved races are the Trans-Am and the Trans-Con. Their rules are effectively the reference for those categories.
To describe the underground nature, to enter the TD: there is no fee, just show up, get a GPS tracker and ride it. There is no prize money, there is usually no crowd at the finish line, there is usually no news coverage of the race. Niche bike media will certainly cover the races, but there won't be a headline in the newspaper about the races and its winners like there would be for the tour de france. The UCI has no jurisdiction on these events. The underground nature is what makes Guiness records kind of moot. It is like saying you can be the best in the world at a sport, and hold records, without that sport also being in the olympics.
Specifically the record in question is tracked as the Fastest-Known-Time (FKT). AFAIK there is no authority on the bevy of FKTs. There are an infinite number of them, and with a number of variations. You could clock how fast it takes to cycle across your home town and be the FKT holder for that. Though, some FKTs are more important than others. Some other big ones are the FKT across europe (both east west and north south), and also for example the FKT along the north south length of Africa.
Trackleaders.com [3] is something of an unofficial-official tracker for these records and events. Trackleaders is not comprehensive, but is typically accepted as a way to record an FKT attempt.
Mark Beaumont is the holder the record for both supported and unsupported (mens) around the world rides. I don't know who holds the record for supported female around the world. It could be that there is no FKT for female supported around the world.
In interviews with Mark Beaumont before he did the supported record, he certainly distinguished between the supported and unsupported record. That wikipedia does not list the differences is immaterial. There are potential additional categories that could be listed, such as tandem and single speed (and perhaps even more whacky like bmx bike or penny farthing. For all of which as far as I know there is no known fastest times). The bicycle community certainly draws a big distinction between supported and unsupported. Tour de France is a highly supported race. Self supported vs supported is the difference between Trans-Am and RAAM (race across america). It is a vast difference between self supported.
This is all similar for how there are a variety of FKTs for sailing around the world. There are FKTs for sailing solo, team, engine powered, sail (wind), and human powered (eg: kayak).
The rules for self supported are usually considered to be those from the Tour Divide [1]
Thus, guiness is not the authority for the rules of this event. Wikipedia not saying anything is just wikipedia being incomplete.
Wiki does list rules for unsupported, namely this: "These rules require riders to be alone for the entire ride, with a minimum 5-bicycle-length distance from any other riders or support vehicles." [2] That rule IS the no drafting provision. 5 bike lengths is commonly considered as the not drafting distance for many bike races. EG: Notably no-draft triathlons.
> I believe in any case it is kind of moot since there is no way for anyone to verify whether the rider drafted or not
I believe this is mostly false for the case of how Lael rode. It is not moot. Lots of eye witnesses. The intent is that the rider is not going to be drafting for hours at a time - that confidently did not happen.
At a pedantic level, it might not be possible to maintain 5 bike lengths for the entire duration, for every moment. To the extent that this is an underground sport, nobody cares because the hard thing is riding around the world. If a person unwillingly drafted for a few minutes is inconsequential. There is a level of honor code at play. The intent is the important part, that any (unintentional) drafting was not a significant factor out of the thousand some hours of riding.
So, the intent of self supported is for sure that you won't be drafting for significant stretches of time or distance (per guidelines/rules listed in the TD. TD usually being considered authoritative for this style of riding). Lael was in remote places, there are going to be no other cyclists around to draft behind. What is more, her live location was publicly available and plenty of eye witnesses - meaning that this aspect could have been validated at any time and was validated by the eye witnesses who oversaw large stretches of her ride.
[1] https://tourdivide.org/the_rules
[2] https://en.m.wikipedia.org/wiki/Around_the_world_cycling_rec...