Tony, a lot to unpack here,
"The shooter had over 200 rounds of ammo" The responding officers didn't know that, but even if they had, they would have been even more motivated to stop him knowing he had the ammo to kill 200 kids.
"Had individual police officers continually tried to take him on with their service weapons, the carnage would have been orders of magnitude greater"
That makes no sense. How would officers continuing to take him down result in MORE carnage? One well-placed shot from a Glock could have ended it. Even if unsuccessful, the officers presence in the building distracts the shooter from killing more kids and causes him to "hunker down". And sadly, every bullet that went into a cop was one less available to shoot kids with.
"Based on how quickly police tend to shoot unarmed suspects that they "fear" plan on doing them harm as they try to run AWAY from the officers pursuing them"
YOUR BIAS IS SHOWING. There are a million police officers in the US. The percentage of officers that have shot unarmed suspects is infinitessimally small, yet you hold that as the typical police mindset? It's not. Most officers have been physically attacked and sustained injuries dozens of times in their careers and never shoot anyone.
"However, I'm not a cop, but I am a citizen. I never expect any officer to senselessly put their lives in danger against common sense odds"
Which is why you will never understand cops. That is what most cops do, at least several times a week. Cops run toward the danger while everyone else runs away. Officers who will NOT put their lives on the line to save children "against common sense odds" are the exception, not the rule.
"The point of this argument is not to criticize the police, it's to highlight that they're at a tactical disadvantage when facing shooters with greater firepower and body armor that makes them almost impervious to individual officers trying to subdue them. One good guy with a hand gun or shotgun has no chance under these circumstances."
It only takes one bullet to take down the shooter, and a .40 Glock is more deadly than a rifle round. The officers may have been outgunned, but they have training and tactical skill which far exceeds that of a video game trained teenager.
Decades ago, the typical response was to set up a perimeter, evacuate and wait for SWAT to make a coordinated tactical entry. Columbine changed that. Officers can't just wait outside while innocents are being killed. Now all officers in US get training specific to Active Shooter Incidents. Immediate entry is part of that training. Yes, it is dangerous for the officers, but I don't know a single officer who won't put their own life on the line (against common sense odds) to save innocent children.
There are a few reported cases where officers stayed outside during an active shooter incident (there was one officer in Parkland, and Tony mentioned a couple cases). The courts did not hold the officers criminally responsible, but they should lose their badges. That is cowardice, and again, it is the exception, not the rule. Can't make that judgement on this case yet, don't know all the facts.