I believe it was on purpose, to show that we haven't learned a lesson, and we never will considering all of the events that happened leading up to the episode with people protesting the episode airing.
The santa thing was probably decided on by matt and trey and not comedy central when they saw most of the protesters were angry with muhammad being portrayed in a bear suit.
when the goo stopped working on tom cruise, it shows everyone is vulnerable to criticism and mocking, and nothing can be done to change that.
on top of all of that, they threw in references to at least 20 episodes and bringing back tons of old characters, i only have one complaint
Where was Towelie?
nevertheless, it wont kill the episode for me. This two parter is easily one of the best things ive seen in awhiile. Its the equivalent of the Simpsons Movie to the Simpsons. During an era where quite a few people believe south park has jumped the shark (usually around season 10), this two parter shows Matt and Trey still have what it takes to shove it in peoples faces and make something very creative at the same time