what type of fallacy is I strongly disagree with your proposal to allow women to join fraternities. Fraternities are "men only" clubs.

Then it can no longer be a man club and it would just be a club. If they wanted that then they should of made it that way but it's for men the main target is men so if women want to be part of these clubs they should just go to a regular club made for both some times men and women need sepret things such as clubs.