> What makes you think it will be any more politically viable to scale out than fission reactors?

IIRC a major difference would be the danger potential in case of a "meltdown", since a fusion reactor wouldn't have kilograms or even tons of uranium etc. laying around to form another elephant's foot but "just" the irradiated reactor vessel which AIUI is both not as dangerous or as long-lived as fission fuel, a fission reactor itself and fission waste products.

Also IIRC the actual "meltdown" of a fusion reactor would involve the reaction environment (extremely high temperatures and pressures) breaking down at which point the reaction stops almost immediately no longer producing any additional radiation or waste products, leaving only the already irradiated reactor vessel to deal with since the comparatively tiny volume of reactant(s) (probably one or more different Hydrogen isotopes) and reaction product(s) (probably Helium) will escape quickly and with pretty much no harm done.