That has always been the mantra and always will.
I'm certainly opposed to God forbids opening new nuclear plants, but I'm also opposed to closing existing ones, those are different arguments and should be treated as such. Nuclear fission is a relic of early 50's, but we already paid the co2 cost of building said plants, therefore should continue operating to reduce further damage to the biosphere by releasing more co2/methane. But we don't need to build new nuclear plants, as they are overly expensive and the safer you try to make them the more expensive they get, not to mention that they take a huge amount of time to actually get built and in the meantime release ungodly amounts of co2 with the colossal amounts of steel and concrete needed for the construction, a co2 budget that will take a long time to be recovered