Glen Cook is certainly old enough to have earned the right to be a bit cranky. He also made most of his living working at a GM assembly plant, not writing books (one of the reasons there was so long a gap in the release of the books of the south). So he's probably not too inclined to have a lot of patience with some random guy off the internet pestering him with questions.
But I also loved Shatner's "Get a Life" sketch on SNL.
I've run into him at a couple of SF cons and he was fine in person, but definitely not inclined to sugar coat things.
I do find it amusing that he's a Power Rangers and Inu Yasha fan.
I am also excited to hear he's working on a new Dread Empire book. The series ended in a cliff hanger, because some visiting fan stole the manuscript and notes for the last book.
BTW, try checking out Jerry Pournelle sometime if you want to see a really cranky writer.