cracked nut holding airbox - best way to remove?

[Mycodex]

I installed an AVO panel filter a while back. When I was putting everything together, I got excited and in my haste, I tighten the bolt (closest to the throttle body that requires an extension) a little too much and I heard a crack. The bolt just spun loosely after that. I tried removing it but it just spun in place so I'm pretty sure that its cracked.

 

Since the bolt wouldn't come out and I had already installed the filter, I just let it go. Now I'm coming up for my 30k service and I wanted to fix it before I go to the dealer if possible. Otherwise, I'll see what they can do although they will probably charge me and then try to snag me for a replacement part. It looks like the nut that holds the bolt is in the frame and i'm not sure how I can get to it. I was thinking of just drilling out the bolt with an extractor. Any other ideas/suggestions that might save me some time?