I can understand why a trans man would wear a bra, since you're not supposed to wear a binder more than a certain number of hours per day. But I would expect them to wear a highly minimizing sports bra, and not let it all hang out like Colt.
I also don't believe she's a DD. Those tits are enormous.
She's lying about not wearing a binder for "comfort" or because "it's hot" the real reason she doesn't wear one is because she wants people to stare at her or give her weird looks so she can cry about oppression and bigotry. It's all about getting those sweet sweet oppression points and satisfying her BPD impulses.