I would argue that the alternative to fossil fuels is “both and”.
You argue a lot of things, as long as nuclear waste comes out as totally fine.
The Finnish model exists and is well regarded.
Well regarded by nuclear fans, of course. Nobody is denying that. Totally unproven to work because nobody tried it, yet. That thing's construction isn't even finished. Check back in 100000 years until making further claims. I'll revoke my misgivings once it's proven to work. Until then don't pile up new waste.