For some reason it took this long to hit me.
If you take as axioms:
1) Countries have major political interest in whether other countries have nuclear reactors
2) Countries are already, at large scale, manipulating discourse across the internet to achieve their political goals
Then of course it follows that any comment thread on a semi-popular or higher site about whether a country should build more nuclear reactors is going to be heavily manipulated by said countries. That's where (most) of the insane people in such threads are probably coming from.
How are we supposed to survive as a civilization with such corrupted channels of communication?
What is, according to you, the political interest?
There are countries that have interest of having gas or oil bought from them. It is not clear if they are pro or against other countries going nuclear: on one hand, nuclear will replace part of their market. On the other hand, lobbying to move towards nuclear may impede progress in replacing gas and oil by renewable (a strategy would be to lobby so that the nuclear project starts and then lobby so that the project stagnates and never delivers).
There are countries that have interest in seeing nuclear adopted because they have a market for the ore extraction or waste processing. There are countries that have interest in seeing nuclear not adopted because they have a market around other generations.
Finally, some countries may want to see their neighbors adopt nuclear: the neighbor will pay all the front bills and take all the risk (economical but also PR, or the cost of educating experts, ...), and if they succeed, they will provide import energy very cheap that can fill the gaps the country did not wanted to invest in.
So it is not clear if there is just one stream of lobbying. The reality is probably that every "sides" does somehow contain manipulative discourse from foreign countries.