having gone to a liberal large university, i had lots of lgbt friends, and a good portion of them at least owned a thong, a handful wore them regularly. my besty and i would go underwear shopping together time to time, but again, it was a large enough and liberal enough city that there was a gay mens underwear store. two even. the same where i live now. i have definitely met a few local guys into thongs via grindr. also, went to Folsom a couple years ago and saw a thong for every 3 jockstraps or so, so a good portion i'd say.
as for straight men, i get that its a little harder and unexpected within your community [the general vanilla populous] but with what ive experienced, yeah its slightly more acceptable and common in general among lgbt groups, because hey we're already one step off the 'norm anyway. but i have also seen plenty of awkwardness, and uncomfortableness around it too, especially with people only recently out and dealing with internalized stuff, and masculinity, and trying to conform and fit within the larger 'straight' expectations. but meh overall folks ive met are all 'you do you'. xD
sorry for the ramble lol