Currently, and increasingly in the future, there is this huge “externality” in the full costs of burning fossil fuels, which is not being connected to the use.
Basic economic theory argues that externalities need to be handled by “non-market” means. Which essentially means regulation.
For whatever reason, the particulars of nuclear power enable enough political will to make a serious attempt at regulation aimed at minimizing (horrific) externalities.
The problem of human induced climate change presents a scary political reality, in which the political structures required to apportion the “true” cost of fossil fuel use might be not be possible. Or possible in a way where the cure is worse than the disease.
If these costs were indeed born by users, the competitive position of nuclear power might be improved.
However, this is not a sufficient argument to relax regulatory requirements for nuclear power.
Also the hundreds of billions of dollars in taxpayer funds that it costs to clean up nuclear disasters. But sure, good to know that nuclear power would be profitable if only corporations didn’t have to comply with all those pesky safety regulations.