Nuclear is not the answer NOW, but it sure as hell could have been if we'd spent the past half century working on that instead of coal and gas as our main source of base load power, but it still can be a useful tool in our approach going forward. In that time we put out a lot more poisons into the environment than just CO2 - coal plants ironically are a much bigger source of radioactive waste than nuclear plants, plus they poison the oceans with mercury as an added bonus. Decommissioning nuclear plants while bringing new coal plants online is nothing short of disastrous.

Speaking of the oceans, they currently contain an estimated 4.5 billion tons of uranium. Global uranium mining operations are currently producing about 50,000 tons per year so it's going to take us several hundred thousand years to catch up with what natural watersheds have already accomplished. How many years did it take us to double the amount of CO2 that nature had already put out there?

The "poisonous waste for millions of years" argument is rather specious in my opinion. The most dangerous nuclear waste from the industrial accidents that people are very rightly worried about preventing are radionuclides like Iodine 131, Cesium 137, Strontium 90, etc. They're extremely radioactive because they're decaying rapidly. That means their half-lives are short as far as these things are measured. By definition they are quickly decaying back towards background levels and will not be dangerously radioactive in several decades, a century at most. More stable isotopes of uranium have extremely long half-lives and will still be undergoing decay in a million years but that is true of all kinds of elements we are exposed to on a daily basis. Potassium in your banana. Carbon-14 in the air you breathe. Trace amounts of radon in your basement. Yes, this stuff will still be poisonous in the distant future but so is lead. When you're measuring the relative risks of trying to survive outside of modern civilization with accidentally gardening too close to an old nuclear plant, honestly it's not even close. PFAs and microplastics are a much bigger problem.

Your concern that nuclear plants encourage nuclear weapons proliferation is fair. There are designs that do not allow for that but they are not showing up in practice yet for a variety of political reasons you outlined, and in some cases they are more difficult to engineer. I'd like to point out that our current trajectory will for sure result in our extinction or at least the permanent death of advanced civilization. We already have tens of thousands of nuclear weapons, so I'm fine with that risk. When you're already swept out to sea, do you care if the water you're swimming in gets a little bit deeper?