[Richbot]

Sounds like the pothole killed the bolt and it took a bit for it shear all the way off. I'm surprised if there's nothing else bent, that's a hell of a big bolt to snap on a pothole. The knuckle is iron and the bolt is galvalume steel. The lower bolt goes through very long runs of the knuckle and it's probably just corroded in there solid if you're driving it in VA winters with road salt

The knuckle needs to come off the car to drill and tap it. He's probably not done that yet because anything can be done with enough persuasion, it's a bastard to get the whole corner apart but if he's going to have to replace the knuckle anyway, worth a shot. But I would tend to agree with them that it's easier and faster (and at any competent shop rate, probably cheaper AND you get a new part) to just replace the knuckle. You get a new wheel bearing while you're in there too! Win!