I would argue that they didn't proliferate due to high barriers to entry. I'm sure any "rogue" states that at one point would be ruled by extremists, would invest in those if it would give them a competitive advantage.
AI can be, or will be at one point, developed at home using consumer devices.
North Korea is dirt poor, but still managed to create nuclear weapons.
The barrier is not that high.
If they could do it then countries like Poland or Finland could do that too. They don't, because they have other security guarantees at the moment. If NATO and EU collapsed - the number of nuclear weapons states would definitely increase.
That ignores the sixty years it took North Korea to develop nuclear weapons. It took the US and USSR less time to develop the first nuclear weapons after the discovery of radioactivity in the late 19th century!
The Soviet Union first began training DPRK nuclear scientists back in 1956 [1] and North Korea only managed to finally build nuclear weapons because of assistance from Pakistan with the uranium enrichment process in the late 90s and early 2000s, specifically the design for the centrifuges that fell into Libya's hands [2][3].
You misrepresent the facts. NK does not attempt developing a nuclear weapon until the end of the cold war and it had access to plutonium at the time of the first nuclear deals in the nineties.
In regard to nuclear weapons the high barrier to entry is mostly because the international community made artificial difficulties in obtaining and purifying the materials. Do not forget that the first nuclear weapons were created with tech from the forties in just a few years. Since then the challenges and possible approaches have become better known and if given the chance and will, any modern country can create them if not for the international backlash.
AI can be, or will be at one point, developed at home using consumer devices.