This kind of logic shouldn’t be taken seriously. It’s in no way an accurate depiction of the path that led the author to their beliefs. Rather, they started with an irrational hatred of the Japanese and then they constructed the most logical sounding argument to support it after the fact.

However, the argument is weak because the idea itself was horribly illogical. But that won’t be a problem for anyone sufficiently motivated to believe it.

Just like all the braindead people online arguing Jonathan Ross was in fear of his life and that Renee Good was obstructing officers despite clear video evidence to the contrary. But they don’t believe she deserved to die for those reasons, they generate the reasons because they already hated her and wanted her dead.

It’s a lot harder if not impossible to round up all the people that hold a given idea, given there’s rarely any external signs - especially if they are trying to hide it