There's next to no chance that whatever comes out of the end of this will be a "liberal democratic Iran government". Obama started a route in that direction with the lowered sanctions and the Joint Comprehensive Plan of Action from 2015. Iran having a democratic government doesn't really help the GOP war hawks so of course they trashed it. The same happened with North Korea in the 90s with the Agreed Framework that had some promise before GWB torpedoed it to please his oinking base.

I also think that nuclear powers mean regional stability. Ukraine gave up its nukes in the 90s and we saw what happened there.