Maybe... but...
I have a TiVo HD player and I have AppleTV.
My TiVo has a horrible Netflix interface, but the movies play pristinely.
My AppleTV on the other hand has that great Netflix interface, yet the movies play horribly (otherwise I wouldn't be in this thread).
Both connected on different HDMI channels to a stereo receiver. I get cable through Comcast.
If you're right, that would suggest that Comcast is OK with TiVos, but not AppleTV's? It's possible. Someone did suggest earlier that there may be some kind of conspiracy to hurt Netflix on other devices, vs. a TiVo which uses Comcast's cable card. Perhaps they view my TiVo as safe since they're getting money off the cable card?