You may have to rip the A-Pillar off so you can get some vice-grips on the bolt head and then pull really hard while you try to spin the bolt backwards. It's a really stupid design and I had the same problem in the 03 truck I used to have. I actually used needle nose vise-grips to get mine out. If you're lucky that will work and then you won't have to rip the A-pillar off. You could also try pushing really hard while you try to twist the bolt off. Once you do get it off then you may have to get the threaded inserts spot-welded so they stay put...