I'm not clear on why your next sentence is:
>But it is clear they were doing it out of bad-faith to the new investors.
Where is the "bad-faith" in caveat emptor?
Every single filing with the SEC contains language that is basically 'holy shit we could go bankrupt tomorrow because billions of reasons' - that's different from "we know we're going down, but we can fleece people on the way down" - though it will be hard to prove criminally in a court for BBB and GameStop, likely.
So I think that the "gluten-free" labels on things that obviously would not have gluten in them (e.g.: bottled water) is absolutely about advertisement to people who have been trained to think that "gluten-free" is always a good thing.
And even within Celiac disease there are a lot of variations. My mother has been diagnosed as Celiac for 50 years (back before most doctors had heard of it, and she almost died from malnutrition pre-diagnosis). She obviously avoids anything that has any mention of wheat, or has been cooked in the same oil as glutenous food; she generally avoids anything that mentions "possible cross-contamination" on the label but doesn't have to be a total stickler. I don't think she's had a serious attack in many years. A friend of mine was diagnosed as Celiac maybe 10 years ago, and is incredibly sensitive - despite his best efforts he seems to end up with horrible symptoms every couple of months or so just through tiny amounts of contamination.
The FDA limit for claiming something is "gluten-free" is 20 ppm; I believe that level exists partly because it's very hard to detect anything less than that anyway, but it also fits in well with what most Celiac sufferers can tolerate.
The short answer is that no, the label gluten free alone does not say anything about cross-contamination.