Really, I think its just part of these new additions the new wirters have thrown on the characters. SpongeBob and Patrick are more immature now what with the chubby cheeks and the one tooth, so SB acting gay is probably due to his lowered level of maturity and seriousness. He is not actually gay if he likes to hang with Sandy. Well in my opinion anyway. The flirting tones towards Squidward? Probably would not have happened if the old writers were still here.
Its complex but I just don't think he's gay there are some things he does with Sandy. Even though the new episodes show less of her now. ... okay now I'm confused, but at least he doesn't walk up to actually kiss any males.