I think Kevin Smith's problem is that he's seeing his core audience starting to wither. His last two movies have had zero to few laughs and even the core group of fans who would generate the solid 30 million box office that would just eek out a profit (before DVD sales, where he usually kills). Apart from Clerks, Chasing Amy, and (slightly) Clerks II, none of his movies have garnered much respect from the critics. He's only now lashing out because his devoted fan base is apparently not so devoted after all.
I will admit here however, I still listen to his podcast and find it genuinely funny when I'm not aghast at just how stupid he is about facts, history, science, the way the world works.