Sensitive, touchy,a lot of conspiracy theory, persecutory delusion.
Never read listIng before buying. But blame everything on seller. very rude.
Not woth doing business with. This guy will cause you lost money, eat negative feedback and much more.
Just don't sell anything to him. This guy will always find an excuse to speculate about The danger your products may brings when there has nothing bad or abnormal has happen yet. then ask for refund for things that normal people don't worry about . If you make a clarify to calm him down, you will get negative feedback.

If we look at The World according to his logic, then everything in the World may brings terrible consequence.

So there is good reason to suspect that this is its modus operandi.His goals are some products price is not expensive, because it has a lot to the probability that the seller will not ask him to return the product (after all, if he returned goods, the seller should bear the return shipping charges, there could be a bigger loss), then blackmailed sellers to give a refund or partial refund, then he can acquire products low price or even free.If you are unfortunate enough to be chosen by him, please do not make any explanation to him, because once you make an explanation rather than immediately give a refund plan, you may get a bad review because he think buyer has privilege, so If seller disagree with his opnion,that is very impolite.
So don't waste time, you can choose to give him a refund and then block him to prevent him from harassing you again in the future.