The fossil fuel suppliers don't like fossil plants being kept online just in case, they like it when the fuel is actually burned in large quantities and then more is bought from them. That's how they make their money.

They did however like to say that renewables would lead to more fuel being burned, even though that never made a lick of sense, because that helped them delay renewables and so burn even more fossil fuels. And some people believed that, even though it's doesn't make any sense.

Nuclear fills that same, "this makes no sense but if you repeat it enough it'll delay progress on renewables and allow for more fossil fuels to be sold/burned" role in right-wing messaging.