Omg, what if a guy presented as androgynous or even feminine? Omg how brave.

Lol. Cis hetero men are way too concerned about making their masculinity crumble in eyes of others. Does it have to do with the weird sense of "respect" which men are often so concenrned about? Scared of being seen as gay or worse yet, trans something something... /sarcasm
Most of the time people will not care, they are concenrned mostly about their own business. Especially at a pool or a beach where people are to have good time. I would guess that getting some dumb fuck shouting at a dude having boobs being extremely rare as they would only make a fool of themselves. Then again, I can't talk about other cultures that much. I come from one in which people mostly value privacy and personal space and they rather just look but stay quiet than cause a scene. Why does it matter so much? Titties or not. Also, guys shouldn't really worry about deviating from gender norms that much. Adult life isn't quite the highschool yard where appearances mean everything. These days its also allowed to be GNC, its allowed to be non straight or look androgynous. Drop the shame, its silly.
Did anybody also think that guys get a free pass of being topless in far more settings than women do? Boobs on a guy is just "Oh he's a bit chubby, oh he has nice pecs, oh he has gynecomastia" I think this is one of the things on which we should be equal in all situations. Who the fuck is scared of seeing a nipple? Or a lump of ducts, lobules and fat below the nipple? They're just a baby feeding stations and that's it.
Here's a nice little challence for all BN folks for next summer, go to a beach or pool topless and snap a pic for a lovely memory.

Zero shame. Boobs are not weird, they're not a taboo. Or if they are, that taboo should be broken already. We're not medieval any more.