I'm not saying Stewie would be embraced by the gay community, but he certainly wouldn't offend anyone. Hell, He's already gay and villainous and there has been no backlash.
Sidenote, making a character an evil gypsy is just as offensive as making them an evil jew. I'm gonna get on my soapbox for a moment and mention that millions of gypsies were murdered in the holocaust alongside the Jewish people. No-one seems to bat an eyelid at the casual racism most gypsy communities are treated with or cares that there are still some countries in the world where they still have no basic human rights. It honestly astounds me how in 2011 it is still seen as socially acceptable to discriminate and be prejudiced against travellers, so much so that many people don't even realise they're doing it.