I just returned from San Diego Comic Con where I sat in on the Glee panel. Ryan Murphy was not there, but a few members of the cast and some of the writers and producers were.
Brad Falchuk (executive producer) clarified that, while the characters of Chris Colfer, Lea Michelle, and Cory Monteith will be graduating from high school, they will still be around. In fact, from the way Brad verbally danced certain topics, I got the idea that they are trying for a spinoff with Chris, Lea, and Michelle.
Brad stated that, while Ryan Murphy confirmed that Kurt, Finn, and Rachel would be graduated, Ryan never said they would be returning to the show.
As for Chord Overstreet, Brad said they asked Chord to return for several episodes. He refused.
You can see the tweets from the panel by searching in Twitter on #Glee and #SDCC
That's mostly what I was talking about, the berating of musicians or bands who won't allow him to use their songs. I also seem to remember him being furious with an extra who posted spoilers about the prom episode, which was obviously very wrong, but I don't see that he behaves much better.
Spoilers released by Executive Producers are very, very different than spoilers released by an extra.