Somehow, Thorium has been the future of nuclear reactors about as long as fusion has been. It's almost a running gag.

(And yes, I know that there are concrete plans for commercial Thorium fission reactors, in a way that aren't for fusion, but still no fully-operating, commercial reactor, afaict).

That's not really saying much given the number of new nuclear reactors of any fuel source the west has built in the current century. You have to build something in order to build something that runs on Thorium.

Just use breeder reactors.

Somebody repurposing the plutonium? No. Plutonium is not plutonium. For a bomb you need Pu-239. The more Pu-240 in your material the harder it is to slam the pieces together fast enough to avoid a premature chain reaction from robbing your bomb of most of it's power.

For both bomb-making and fuel breeding the desired reaction is U-238 + n => U-239, decays to Np-239, decays to Pu-239. There is also the reaction Pu-239 + n => Pu-240. The power guys don't care, Pu-240 works fine. The bomb guys do care. Thus the power guys leave the fuel in the reactor until too much neutron poison builds up. The bomb guys leave the fuel in the reactor only a short time.