I get what you're saying. I just think it's easy to say that when it's not you that's being warned for. That's where the objection is coming from. Queer people in their real lives are often treated as something objectionable, so they object to a classification that suggests it in fandom.

I increasingly think that the real problem is the label "Warning". Some things do need to be warned for, e.g. underrage sex, because in Australia you can actually be arrested for reading it. Most thing are just a question of preference, though, so a label like "Content" would solve it neatly.