Let's not be too hasty now. It's just one of those things that could be taken the wrong way because of certain stereotypical cliches found in a lot of non-heterosexual characters, many of whom were poorly written out of, well, ignorance, for lack of a better word. It's not something many people seem to be aware of and I'm sure that comic isn't meant to cause any offence.
Anyway, since the writers are pretty damn serious with characterisation, it's certain that Dorian (and Sera) won't be the "pesky homosexual cliche" who hits on or ogles over heterosexual men/women. I mean, I actually don't see that happening, to be perfectly honest. Dorian's just more concerned with righting wrongs in his homeland and seeking personal freedom to live his life how he sees fit.