SilverWook said:

I often wonder if Lucas is aware of this, or gives his blessing simply because his kids like it.

I doubt he really gives a crap. He seems to be all supportive, but that is probably to draw in fans. He already has enough fans (most of us) mad at him, he doesn't need to lose more by revoking Robot Chicken poking privileges.

In the case of Family Guy, he has Seth MacFarlane in his pocket. Telling him that (Doubtful) "I TiVo every episode of Family Guy" was probably to get more fans as well.