So they're going to go back to corn husk brooms? Where do they draw the line?
I'd say they just did. They're sticking with what they have now, and not using the newer, better technology.
In most sports, there is an intersection of skill and technology. In order to keep things interesting, you typically want to increase the amount of skill required, and lower the amount of technology. However, there are times when that may sway one direction or the other- safety is an obvious exception to the above.
There is no reason to insert fallacies; this is normal and has been going on as long as sports have existed. The only interesting thing here is that the top teams are taking a stand before the ruling body makes a declaration. That will still need to happen, but this will likely sway the decision made.
They can't just add a rule that says you can't use Brand X equipment - it has to declare limits on what the equipment is.
The key here is that the professionals claim it fundamentally changes the game. Not only does it allegedly drastically change the dynamics of how the rock travels, it also allegedly takes most of the skill requirement out of shooting and puts it into sweeping. Not to mention it also supposedly causes significant harm to the playability of the ice surface, which is paramount in curling.
Somebody posted a video on youtube (https://www.youtube.com/watch?v=ScelTWytLFQ&feature=youtu.be) of a draw shot that the sweeper was able to manipulate the rock into traveling a straight line, while a rock a few feet over curled five feet. This sort of manipulation completely changes how the game is played, both physically as well as strategy.
Now, I'm still not sure I believe all the claims, and the video leaves a lot of unanswered questions, and some claim it's just a smear campaign by BalancePlus against competitor Hardline. I don't know what to believe, and am reserving judgement until the evidence is more clear. BUT, if these brooms can in fact do everything people claim they can, I would be in favor of disallowing them.
I think if they are going to look at putting some sort of rule in place then they need to look at it from something that can be strictly scientifically measured, like the rebound velocity of a golf club face, rather then something against a specific fabric type.
If you watch closely you can see the sweeping appears to cause the rock to change handles multiple times, which would explain the straight draw shot. I mean, I've played on some very straight ice before, but never that straight, unless there was a problem with the ice itself. Even the straightest ice moves a couple rock widths on a draw. There are some shenanigans going on, not necessarily with the brooms.