Maybe he has a Walmart connection and is perfectly happy with lag comp?
They should start worrying about it though because it's more noticable than MW3. More people are getting better connections so if this is going to be their response it will eventually hit them in the pocket.
It would be unfair to say that Treyarch isn't supporting the game post-launch, because they are. Look at the amount of changes listed in the notes of the upcoming patch.
Are they small? Yes. Are there bigger problems left unaddressed? Yes.
The answer might be as TC stated. Vonderhaar may feel that by acknowledging the existence of the terrible lag issues the community has expressed, sales might be hurt. However, they haven't abandoned the game, and I might even gamble and say that their might be a fix undergoing construction during this period of ironing out the small wrinkles. The lag fix may be massive, however, perhaps too big to foresee its arrival anytime soon (which might be another reason it hasn't been acknowledged). It will remain at the bottom of the priority list, too, if Vonderhaar's game is to keep quiet until Christmas passes.
Who knows, maybe a fix will get dropped on us in January?
Anyways, to those who say that it shouldn't be ignored simply because people will buy it regardless, I don't have an answer. It's Treyarch.