Tbh this. We've come a long way from "sorry girls I'm GAY XD" Sasuke/Naruto. I think being upfront about shipping or not is only a good thing, especially when people are dubious at best about keeping up with people's permissions. Sure it might have been a little rude if it went like this:

OP: Hi this is my character (female).
Other Player: SORRY HES GAY

But still, tonnes of people rp to ship and focus on that aspect of it. Being up front is just a good thing (though I agree with it being rude if that's how it went down).