I love how people shit on Gabe over the early release L4D2 vs Ep.3; but, as I recall Minh Le (aka Gooseman) and the rest of the Counter Strike mod creation team were the guys who do L4D, and they get to do things pretty much however and whenever they want. I think I read in more than one interview that Minh didn't want to be a game dev. and really didn't want to be part of the industry unless he was given broad authority. (No surpise that would be overlooked as the GGT is full of Bold Statements).
That being said, I haven't read an interview with him in a while so I can't really say much on his opinion of L4D2's timing (other than what I already know).