I haven't seen either episode yet, but I hope to soon.
That being said, I read an interview with Trey and Matt a while ago and they said they absolutely hated family guy, so its not a big wonder why they did this.
They felt that family guy was too immature and brought down animated comedys to a level of stupid that their show didn't. Yeah, South Park sure doesn't have all the toilet jokes nor does it have all the other immature jokes that family guy does.
From that interview, it seems as though Trey and Matt think of animated comedys in the following light:
1.) Intellectual
2.) Stupid
They placed themselves and Simpsons in Intellectual and everyone else in stupid.
To be honest, I think the only difference is that they do a better job of tying in intellectual stuff, but all of them get their laughs off of shock value, and a lot off of toilet humor still. For them to place themselves above family guy, when you look at stuff such as the teacher getting a sex job, the vehicle he invents that goes into your anus, the alien anus probe, terrence and philip, all the sexual humor that happens, the whole environment episode that was about farting, etc, I just think that the ONLY reason that they could even be considered "less stupid" is by the fact tha they try to incorporate current events into their stories, whereas family guy doesn't.
They still rely on the same stupid sh-- that the other animanted comedys do. Oh and guess what? They're all funny as hell!