Renewables still have holes in their capacity especially for more environmentally unstable regions. Got clouds solar efficiency is fucked, also pollar nights exist in some places. No water? Hydro is a non factor. Wind can in theory be maintained anywhere but has some scale issues that a military base either doesn’t want to deal with or can’t. Finally battery tech is so and so, perhaps in a decade or so it’ll be advanced enough to overcome a lot of the limits but there’s still some issues.

Nuclear is honestly the best we have for a relatively low maintenance easily stockable power generation system. Plus here’s hoping it succeeds and reinvigorates interest in nuclear ships, kind of a shame that project was shelved during Eisenhower’s admin.