I've been thinking this Shane Gillis comment for a while, and I now have Opinions.
Necessary disclaimer: I don't use the word "whore" so I wouldn't describe this particular gymwear style with it. I would rather say "borderline inappropriate" or even "inappropriate"; more of that later.
This isn't so much about Gillis' joke, as it is about the reaction to it and this particular strand of gym fashion.
First of all, I think this "we don't dress this way for attention" doesn't make any sense. Any woman who wears to a public place a (at times a push-up) sport bra and tiny, gossamer shorts that she deliberately pulls up between her buttocks*, is in my opinion at the very least looking to show off.
But I don't think they're looking to show off to men, at least not necessarily. I think they are to a great extent looking to show off to other women, as a mix of both competition and fishing for admiration. Women are socialised to gas each other up anyway, so expecting "yess girl" type of comments for "cute" outfits makes absolutley perfect sense. Especially when they post selfies on social media. We already know this phenomenon with men, where they show off their gains in muscle shirts or selfies, in a clearly homosocial display. In fact it is such well-known behaviour that it's the butt of a lot of jokes. I think women are (now) engaging in exactly the same thing.
Now I don't think there's anything wrong with this, not as such. If one wants to show off to gain validation and compliments, that's fine with me. But it would be nice if people were honest about what their doing.
Second of all, I do think this clothing is straight up inappropriate for a public gym. You go there to work hard, and that means sweating. And personally I do not want your midriff sweat rubbed all over the benches, backrests and other equipment. Put a damn T-shirt on, and use a towel for good measure. And same goes for butt/crotch sweat for those whose shorts are barely long enough to cover their butt cheeks. I don't care if you wipe your equipment afterwards, I would much rather the skin-to-device contact not be there in the first place.
I'm going to take a page out of Joey Swoll's book and say that if you want to train like that, build a home gym, train there.
The gym I go to has in fact a rule in place, that forbids the use of sleeveless tops while training - for everyone. And I think that is an excellent rule for a gym.
And no, I don't buy the "comfort" excuse. Gyms are air-conditioned spaces, I'd be very surprised there was one hot enough that one actually needed to wear what amounts to a bikini, to avoid overheating.
*No, I'm not lying, this is actually a Popular Thing.