It's not that having a preference is problematic. There's a huge difference between trans/disabled chasing and being open to dating trans and people with disabilities. Chasing is a sort of fetishization mixed in with some dumb ideas about what masculinity is. Whereas a preference in dating is more along the lines of 'i like you and that part of you, you like me, let's do things together that we like.' The difference is about respect and equality in the relationship.