I agree 100% that you can tell people "on day 1 that under these circumstances, the expectation is that you go in and attempt to neutralize the threat, and at the very least draw their attention and fire away from the kids." I can also look at cops behavior or Parkland, at Uvalde, and at other non-school shootings. They don't do what they're supposed to. That's bad - full stop.
Yes they should go in. But they don't, not with actual training. I am not arguing with you or @Brisketexan about what cops SHOULD do. I am arguing about what I think realistic expectations are for poorly-trained bullies who aren't used to actually being fired upon. The cops here weren't exceptionally bad - this should be viewed as just the baseline shitty behavior that should be expected, which is why the solution isn't more cops at more schools. It won't work.
Anyway, I've said my piece on this - can agree to disagree.