Heterosexuality, and sexuality in general, is broad and a spectrum. To say that someone who sees themself as a man must not find trans women attractive in order to be straight both undermines the nuance of heterosexual identities and invalidates the identities of trans women. No one is demanding that every man who sees himself as straight finds trans women attractive. But to imply that it's as simple as "man like pussy" is reductive at best and transphobic at worst.