Can you expand? What is “poison” referring to? Surely, burning coal as Germany’s current pace can’t be seen as a success, can it?

Radiation poisoning. Fossil fuels fall into the same category. The alternative is not nuclear vs. fossil. We should focus entirely on renewable energies. Of course Germany is now in a transition period, and there are a lot of conservative politicians who have been shying away from the high investments required for a fast transition. I think the main problem here is that the fossil-nuclear advocates shift the main problems to future generations (climate change, long-term storage of nuclear waste), the general public (large subsidies, minimal security standards, no or unsufficient insurance of power plants against desasters) or other countries (placing nuclear plants or waste deposits at the border, relaying on other countries for long term storing of nuclear waste). Together with extremely optimistic estimates, this makes their energy costs appear low on paper, when in reality the overall costs are immense. In contrast, there do not appear to be many cost elements of renewable energy installations that can be concealed or embellished. The reserve funds for their demolition are perhaps the only exception. But these only account for a small part of the costs at any rate.

And nuclear could have drastically reduced that production of "poison" by the way. Arguments about how much we've contaminated with X are sort of immaterial to arguments in favor of a different thing with its own much more specific (and useful) dynamics.

It's a bit absurd, what you say, like arguing that it's good to stop using a stove in your apartment and just eat food raw, because one of your neighbors already did enough bad because they burned their entire house down while trying to make a bonfire with piles of coal in their yard.

I am not saying that. I am saying that you should use renewable energy to operate your (energy efficient) stove. The technology is here.

Using renewables makes a lot of sense, but the sun doesn't shine all the time, you can't control the wind or the rain, and batteries don't have unlimited capacity. You still need something that starts producing electricity at a flip of a switch. Fusion might do that in the future, but until then, you'll be burning coal or something like gas (which you don't have locally) because the alternative isn't perfect?

Geothermal energy is constantly available. Offshore wind parks can provide a stable basic supply. Energy storage and grids that connect distant places can mitigate local variability a lot.

I would not advocate against having some fossil emergency backups. I think the planet can cope with a few percent of that. If this were our only concern, then we would have basically solved the problem.