Interesting thread. I've followed gymnastics for a very long time, but cheerleading I've only really payed attention to since that Netflix show Cheer started (and I haven't even seen it yet. But it sounds interesting).
I would say that if I were that buy and focused on my training in that sport, I wouldn't spend much time “turned on”. I'd be too focussed to be horny about anything. That said, cheer is a very “All-American” activity to be involved in, and being seen is very important for most teens and early 20-sums. These activities usually breed popularity with the “cool crowd”.
All that having been said, I follow athletics at my local large public university. Until COVID-19, there was always this 80+ year old man who would be seen at all the female sporting events I'd go to (volleyball, tennis, soccer, etc) and a few men's things. He was ALWAYS chatting it up with the girls, be they the athletes of the day, or the cheer and dance teams. And he'd always dress in an overkill fashion in all the school colors. It always kind of made me uncomfortable, and made me wonder how many creepy guys the female athletes (including cheer/dance) have to deal with. Especially much older guys.
All that said, the sexuality in those sports is certainly not lost on me. I'd be deluded if I thought otherwise. But I imagine if I were in that position, the appeal would be a combination of popularity amongst my age peers (platonically and not), the general excitement of gameday, and maybe the outfit, because obviously cheer outfits are a fetish. Community and discipline are important as well. Plus, any one of these extracurriculars that students engage in can help them into the job market somehow. Cheering for NBA/MLB/NFL teams, cheer coaching, cheer admin, cheer fashion design, etc.