I haven't read this entire thread (sorry, 8 pages is a whole lot) so pardon me if someone has already touched upon this, but I think Spongebob handles homosexuality rather carefully in a few of it's earlier episodes.
For example, there's an episode where Spongebob and Patrick adopt a baby mollusk, and as a result, they take on roles as Mommy and Daddy. Complete with Spongebob wearing drag (curlers and a nightgown). Here's a situation that is "normally" (the word in quotes for a reason) attributed to a man and a women, and in the episode we have two men on the job, with one acting as the mother. Is this so different to what actual gay couples do? (Maybe one doesn't necessarily take on a "mother" role, but you get the idea) And the episode was still just as funny, and just as silly, and kid-oriented as any other, but it explored a different theme to parenting. If more children shows could do this (or Spongebob could go back to being good, instead of brainless) and could do this just as tastefully, then why not have these kind of themes explored in children shows? Maybe if kids grow up seeing that its okay for a girl to like a girl, or a boy to like a boy, they'll be mindful in the future not to pick on someone for their sexuality choice.
And if you're one of those people who believe that homosexuality can be indoctrinated into another person, and therefore showing kids gay characters is going to make them gay, then you're just silly.