Why do I think this is FUD?
A) they didn't already have nukes
B) making your own x86 processors were a prerequisite to nuclear technology
The processing power at oak ridge et al AFAIK is spent trying to recover old warheads without testing them, which is a massively harder problem.
Edit: and the Chinese have had their DD-ZF publicly for years now. I feel like they have to have warheads for it. Given where we've known about what warheads they have when, it'd make sense for that to be available currently.
It helps in the future but for this scenario, it makes not difference.