My pragmatic side is inclined to agree. There is a certain degree of professionalism you'd expect out of high-profile writers; after all, if DiDio had gone off on anything remotely resembling such a spiteful rant against any of his writers -- and I'm sure he has a bunch of horror stories he could share if he were so inclined -- we'd all be on his ass in a second, and not in the fun way.
My fanboy side, though, says "LOL! DiDio SUCKS I can't believe he SUCKS SO HARD! Go Waid! Tell it like it is! It's all fair game, bitches!!"