Need another mechanic tip: lower ball joint studs turning with nuts?

Mine don't have studs but rather HH bolts

But if I had your stud problem; there are at least four possible solutions
1) grind the head off the stud, and punch it out
2) tack weld the stud to the spindle
3) heat the nut up cherry red,let it air-cool, then spin it off with an impact.
4) torch the nut off
5) if I absolutely had to save the "stud", I would weld another bolt , or a rod, crosswise across the head of the rivet and use it for a handle.

99) I would not put a stud back in there. On my Barracuda, that bolt is also the stopper and goes in the other way; the bolt-head having a round head, it bangs into the LCA to limit steering angle.IIRC the knuckle is threaded, and the nut is on the disc side. That washer is not supposed to be where it is either, but may have been installed like that, to adjust bump-steer.