If soviet russia's PAL locks were built anything like US's security measures where it's actually subtle timing information they would have to rip out and completely rebuild the explosive shell that trigger the nuclear reaction, at which point you essentially are creating new nukes from scratch.
1. It's not obvious to me you can't reverse-engineer the necessary timing information, especially when you have a bunch of nuclear weapons experts and a huge stockpile allowing you to take apart a few and use that knowledge on the rest. To my knowledge, the PAL system was intended to prevent weapons from being detonated by rouge officers or thieves; it wasn't designed to thwart states.
2. Even if all the conventional explosions are worthless, you still have all the nuclear material and other extremely sophisticated equipment involved with boosting, etc. It's not like creating new nukes from scratch.
I think for this conversation to continue productively, we need experts to weigh in on these issues.
