First off, TERFs are the ones using it; second trans men don’t have the same institutional power cis men do, so you can’t say they are part of the oppressor class, and if a group of men cannot be considered part of the oppressor class, how can you say men as a whole are oppressors? Now this can apply to other groups of men, like men of color, queer men, disabled men, etc (so you know), but the reason I’m saying this arguments are transphobic is because minority men often have power over minority women and TERFs use this as a way to insist that yes, men are oppressors of women because they will oppress women in their communities; but trans men and other trans masculine people are always exempt from the oppressor group, why? Because they’re AFAB and therefore not “real” men.