you are right, there is not much reclamatory or rebellious on a societal level about cis men (in their role as such) taking up the space they need and even less so, when they take up more space than they need.
i think it is still positive when people - including cis men - overcome their insecurities and take care of themselves. but i understand if that is not what you meant with your post.
i would give the commenter the benefit of the doubt tho and assume that they are not a troll as well as even restrain from assuming their gender and therefore the reclamatory value of their action.
personally, i still struggle with internalizing that i can sit comfortably on public transport without that invalidating my feminitiy or making me a toxically masculine man
a cute person once info dumped to me about which things are berries and which are not :3