words can cause thoughts, thoughts can cause urges to perform actions which are harmful to oneself, such urges can cause actions which are harmful to oneself. There’s no claim that any of these things is particularly likely, just that they’re possible, and if they’re all possible, then it’s possible for words to cause harm
Without having an object level opinion here (I didn’t read the post and I only skimmed the comments), I note that this argument is incomplete. It may be that the set of “urges that cause harmful actions” is disjoint from the set of “urges which can be caused by thoughts which can be caused by words”.
Seems worth mentioning that the four ways you list for events to be causally linked are the building blocks of d-separation, not the whole thing. E.g. “A causes X, X causes B” is a causal link, but not direct. And “A causes X, B causes X, X causes Y, and we’ve observed Y” is one as well. Or even: “A causes X, Y causes X, Y causes B, X causes Z, and we’ve observed Z”. (That’s the link between s and y in example 3 from your link.)