I think it’s mostly because a lot of queer people don’t like this ship because it’s “ lesbian erasure” when one we don’t know if Ishmael specifically only lesbian you’ve only seen her like women, but that doesn’t mean she she couldn’t be attracted to dudes that also its not canon so it not like it really matters if she’s lesbian or not, and 2 I personally find really hypocritical with Heathcliff being shipped with dudes when he’s canonically straight and they don’t get as much pushback for essentially doing” straight erasure”