I prefer tank top myself. Men's armpits can be pretty smelly. Short-sleeved or long-sleeved leotards start to really stink on me really quickly. It's even worse than with T-shirts because the leotard is closer to your armpit and just soaks up all the sweat.
I'd guess that's probably why men don't usually wear long-sleeved leotards. But if you want to deal with the practical issues here, there's no reason why not.
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