i always like it when people paint a big "fire me now"-sign on their forehead. it's bold, it's cool and he will find another job anyway (or maybe start a startup instead of just bitching about them)
If the post is taken down, it will be re-blogged by every other tech pundit from Gruber to Dvorak (hello, Streisand effect.)
If AOL repremands MG Siegler, then everyone will know what happened. Either he'll do another post, or he'll blog about in on his personal blog and it will take off through the bloggeratti. If he's forced into silence, then it will leak out through friends and colleagues.
If AOL ignores it and does what it wants, then the writers at TechCrunch will at least know what they can get away with. It's the Mindsweeper's Dilemma, you can't make any progress among uncertainty unless you take the first step.
MG Siegler probably thought (correctly, I think) that he's not at risk of getting fired and the uncertainty is killing morale.
If he is fired, he knows some other tech blog will snatch him up.
So, it may indeed seem unprofessional, but I give him a lot of credit in trying to "manage up."
In a few months, everybody is going to forget about this whole the episode anyway. Firing him or giving him more ammunition is exactly what they don't want to do.