"Reason: Talking about such violence makes that violence more probable,"

Does it? In some cases yes, and some cases no. Wacky people advocating violence can be smacked down by the crowd. Wacky violent loners need perspective from other people.

Talking about socially approved violence probably makes it more likely. Talking about socially disapproved violence might make it less likely.

The problem with these conversations are the generalities involved. We don't have examples of the offending material, and worse, the whole point is to hide the examples of offending material.

SUGGESTION: Move disapproved posts to their own thread where replies aren't allowed. Wouldn't you get some brownie points from the people you're trying to impress by showing that you ban all this stuff you think they disapprove of?

My guess is that the policy will be applied reasonably, and were people allowed to see what was banned, they'd think so too.