That’s not true, it’s actually quite the opposite: If you are still supporting nuclear energy then you have not informed yourself about the state of the environment. It only makes sense in toy models these days.

Those who care about the environment right now and pleading for us to reduce our consumption first (degrowth), and then second to transition to cleaner sources. Nuclear is not a preferred cleaner source in this initial phase for many reasons including: poor resiliency to climate change, too slow to bring online in time to facilitate immediate reductions from other sources, risks based on complexity (such as supply chains), invariant energy production, and I’m sure many others.

In the unlikely event that we stabilize climate change before hitting a civilization-ending tipping point, nuclear becomes more attractive again. Until then it is often considered by climate scientists to be counter-productive.