The Muppets aren't organizing the march per se, but one part of your comment is not completely correct. I have researched and discovered that PBS is being VERY vocal about Romney's statement about cutting funding to PBS. So in essence, they have become very much involved in this political race. PBS in one of the articles is promoting for people to retweet its case involving Romney's statement:
"Later on Thursday PBS promoted a post on Twitter – where the main case in its defense had been made – describing itself as "trusted, valued and essential" and asking others to retweet. The post linked to a website stressing the value of the service."
Blaming the "Obama suporters" sounds like yet another LIE from the GOP. PBS is in fact expressing their outrage for the threat of losing finding because of Romney and thus have been forced into politics thanks to Romney.