He didn't say that Dunn got what he deserved or delight in his death. Before he tweeted the infamous tweet, he commented in another RIP Ryan Dunn. He has stated he has empathy for alcoholics given that he was one himself, nearly dying in a car accident. In one blog post (or more) he explicitly stated, there but for the grace of god go I.
He stated that friends (or JAs, ie the crew of friends in question) don't let friends drive drunk. They shouldn't. This was not an offensive expression. I'd say it's a sorrowful one as this was a death, well 2 deaths, that was avoidable.
It was soon, but it wasn't as though his was the first comment on the subject. Again, he didn't glory or delight or gloat in what happened. He expressed a thought that was relevant, valid and timely.
It's not speaking ill of the dead or making light of the loved ones' pain. It's acknowledgeing the pointlessness of what happened, the sheer avoidability of what happened.
Russ Meyer is certainly an acquired taste. I myself preferred Beyond the Valley of the Ultradolls, thankyouverymuch.