Quite the opposite, there's clear evidence that fossil fuel companies heavily supported anti-nuclear action groups. Because nuclear energy is just as much of a threat to their business as renewables are.
Fossil companies fund both camps. They are especially interested in closing-down existing nuclear plants, as it immediately creates a big market for them, but it's also useful to them to delay deploying new solar/wind capacity (and thus, funding the wait-for-new-nuclear or even wait-for-fusion campaigns)
Solar is the solution now because America dithered and fumbled nuclear energy in the 60s - 80s. Now nuclear cannot be built because every estimate has been 1/10th the actual cost for plants built in this millennium. Glow rocks are dead - use fusion power from the sky.
Then they’ll attack nuclear and, maybe, promote deep water thermal differential ammonia generators or geothermal sources.