I don't think that Rarehero and Seth MacFarlane are the same person, so your opinion of the show he contributes to have no bearing on the work he does as a professional for Family Guy. It's like saying "I hate the Yankees therefore anybody who works for the Yankees in any capacity sucks and deserves to be mocked".
Transformers, the 2007 movie, was nominated for Oscars in visual effects and sound editing and mixing. I have many harsh things to say about that movie, but that doesn't mean I take a crap on the professionals who earned those oscar noms. Who would? Only trolls and idiots.