A couple of points.
I don't think it was WoTC that brought him "out of obscurity", but the rise of the Internet itself. Gary did not start using the Internet himself until around 1996, and he started by having informal chats on Marcray's Keep, had a web site for a brief period, and setup some mailing lists.
While 3e might have brought some attention to EGG, I also think the thing it brought was a more "indirect effect" through all the web sites, most particularly ENWorld and Dragonsfoot. Gary also sort of got inspired by the latter because he realized there were what he believed to be a loyal number of people who stuck with 1st Edition.
As far as Gary's opinions, he hated what he called "political correctness" and never wanted to hide his opinions on subjects. I personally thought he could be a little more diplomatic, but that wasn't his way, and I respected that. Note that there are forums like that--ENWorld is more strict about rules regarding edition wars, others allow full flaming. I do know that when you met Gary at a convention, he was usually polite and from what I saw (unlike some old-school fans) he did not attack a player of RPGs in general. People also need to remember that EGG occasionally used "Puffery" in his writing and his opinions (as noted by Robin Laws) tended to sound more angry in writing than in person.
Did having a stroke change Gary? Well, if you think the opinions on D&D changed because of it, you'd be mistaken, as early as 2002 I saw changes in opinion about the new game. I did see some changes--I think the stroke inspired some enhancement of religious faith, that's the most direct thing I saw. He went from being a strict libertarian to a more social conservative--we had a talk list for political discussion and he went from forwarding Harry Browne articles to WorldNetDaily and Ann Coutler articles. But that might have started after 9/11 and the Middle Eastern Wars, so I can't even blame that directly on the stroke.
So, I don't think he "owed" WoTC anything, more likely the Internet. I don't see them directly responsible for putting him on the map--clearly the fan sites, as well as the partners he worked with did more than WoTC in my mind.