FYI the reason we never have to define "man" is because men are not bothered about women claiming that they are men,
To be fair, some cismen reject transmen also. Although probably more due to conceptional disputes than due to beliefs of some sort of agenda to "erase" men and do down men and so on.
But speaking for myself, it is all just words really. As a man I have never had a single exclusive label to denote those with an XY and no other subgroup of humanity, as in certain contexts the word man refers to us all, all humans.
So if the word squired a new meaning where men can refer to cismen and transmen collectively, well as I say just words.
Only time I would be concerned is if there is a context in which it is relevant and necessary to take in bio-male physiological differences, and this was not being done. Otherwise, in the general scheme of things, call me a a human, a person, a man (biological XY definition), or man (belongs to the group of cis and transmen). But again, speaking only for myself.