Just a point of order, Clark was indeed the primary 4e/GSL 3pp cheerleader for quite a while. He was continually effusive in his praise of WotC, Scott, and Linae, and was workign with them (on phone calls, etc.) trying to understand and then later get changes to the GSL. It's all on these forums, here's a representative thread ("Orcus" is Clark).
New GSL Announcement - EN World: D&D / RPG News & Reviews
Bonus quotes: "I dont have new 3E stuff on my mind at all. I am firmly 4E. I was just going to provide that as an accomodation to fans. Thats all."
"I dont think anyone should be mad at Wizards either."
"It has become abundantly clear to me that some people are just going to complain and look a gift horse in the mouth. No matter what they get, it wont be enough. I dont endorse that thinking at all. This is not war on the OGL. Go, use the OGL all you want. Your ability to use the OGL today is no different than it was before this announcement and before you had a GSL. If you are happy using the OGL then you shouldnt care about not using the GSL."
He was so much a booster that when he finally decided not to sign the GSL when it first came out I called him out as a "flip-flopper" on my blog! (With love...)
No comment on the rest of the usual arguments, but pretending that Clark wasn't an avid banner-waver for 4e and the GSL is disingenuous (or just ignorant of the historical facts).