Fusion will be slow to commercialize. Proof of concept is going to be much harder than for fission reactors. But if and when POC is attained, building commercial fusion reactors will not have as nearly much project risk, much less waste management risk, no proliferation risk, and much less financial risk in decommissioning. If you screw it up you can expensively damage your reactor, but you don't spread fallout, and you don't have to guard your waste like it's plutonium.

Neither fission nor fusion are going to put any juice on the grid before the AI bubble resolves, and then the financial calculations will be totally different.