It’s a red herring. A door was left open? OMG! Doesn’t excuse armed LEOs standing around outside while the killer killed.
No, it doesn’t excuse that - but it certainly isn’t a red herring since it would make a difference if that’s how he got in...that’s kind of a major difference in outcomes if he could not get inside the school.
Yep. For years schools were left with doors unlocked, even post Columbine. IMHO, some of these shooters see it as a game to see how they can defeat the security measures. The issue is the totally inept response by the School Police.