It's one thing to not want to date a trans person because you're not sexually ATTRACTED to trans people. That's perfectly fine. To not want to because it's "against your ideals" implies that you disapprove of ANYONE dating a trans person

No, that's what it implies to you. Not to everyone else. And idk why.

It's simple. "I wouldn't date a trans person because it's against my ideals" implies nothing about the rest of the world. It just exposes that the speaker's ideal sexual preference does not include trans people. Now, if you're choosing to take "ideals" as "ideals about how society should work", that's on you. If you're choosing to take "I wouldn't date" as "nobody should date", that's also on you.

The phrase is simple and already explains sexual preference, not view on society. It's actually really goddamn interesting, because OP was illustrating how hard it is to draw a line in the sand, because someone will cross it and say you're not allowed to draw the line there, and you did that exact fucking thing. You likened drawing that line in the sand with drawing EVERYONE's line for them, and swiftly crossed it, expressing how wrong it is to draw the line there, and where everyone else's line should be, because you know better and are reading into the implications.