With great power to parody comes great responsability. The disclaimer stating that it is a parody protects against all most all threats they will face on their long journey. Godspeed, you kings of the ocean.
Well, it’s a parady so it’s protected, but Schultz’s estate is sue happy I wouldn’t be suprised if they try to sue. It will certainly get thrown out, since as said parody and satire are protected, but that doen’t mean they won’t try.
IIRC, Sarah Michelle Gellar voiced herself in the “… and that’s how Buffy season 8 would have gone,” which was hilarious.
Heck, the very first episode had the “this is your brain on drug commercial” voiced by the same girl as the original, Rachel Leigh Cook.
Although Jean Schulz did complain about a Saturday Night Live parody of A Charlie Brown Christmas, nothing was really done about it.
As for “Schulz’s estate,” they do not own the characters- United Feature does. And as far as I know, they really haven’t sued anyone over a bona fide TV or magazine parody (MAD magazine parodied the strip so many times that the Schulz Museum recently had an exibit about them), but if you misuse Snoopy or Dilbert on your website, the letters will come a-flyin’.