If I were to ban posts on the grounds that I consider them bad for LW, I would ban maybe a quarter of Discussion posts.

I'm not sure it would be a bad idea if you started banning posts on this level of super-obvious crap. I'm also not sure it would hurt to have you ban a quarter of Discussion, but I'm a lot more optimistic that nothing bad goes wrong if you consistently ban everything this horrible.

I agree that it's better for that post to not be on LW, but banning such things is not standard procedure, and people don't like it when moderators do surprizing things.

It is not clear to me that this should be an important consideration in restraining moderation. If some people, including some good posters, who don't like "surprising moderation" leave and what's left gets more surprisingly moderated because moderators are less worried about consistency, then it's not clear to me that this is net worse. There's a startup cost to more vigorous and less consistent moderation, I think it's already mostly been paid, and then once that cost is paid, maybe things decline more slowly. Maybe they don't. It does not feel to me like leaving absolute obvious crap on Discussion because I'm worried about someone reacting poorly to a surprising moderation, is really much of a net improvement to the expected future.