in such a world presumably more physicists would be super-rich.

In our world, there are various weapons that could be used to kill at least as many people as a nuclear bomb would. GE plague is one, and it's easy to believe that in the near future a competent biologist would be able to engineer a usable bioweapon at home. With that alternative in mind, I would love for GE bioweapons to only be accessible to super-rich biologists.

There are fewer super-rich physicists than there are ordinarily rich states who possess nuclear weapons. Plus, 90% of the actual use nuclear weapons get is deterrence, and secret nuclear weapons are useless for that. OTOH, for garage-based first strike capacity nuclear weapons aren't required, there are also bioweapons etc. That's why I'd rather the physicists had a monopoly.