If you're one of those 2 officers how do you not make it your mission in life to take out the other 394 idiots on scene who prevented you from doing everything in your power to save your family member...
A couple things.
I don't know about the one who's daughter was killed, but as for the one who's wife was killed:
1. He was one of the first responders (is seen entering the school with the very first group who arrived). While he may not have known his wife was shot, or maybe she wasn't even shot yet, he was in a position where he could have acted and did not. So it would seem he had no intention of doing anything UNTIL he found out she was shot.
2. I fully agree many there deserve a ton of blame (at the least), but it's a bit hyperbolic to blame every cop who responded. I think we can all recognize that not all of the 300+ there were in a position to, or had the knowledge of the situation to have personally attempted to engage the killer. I don't blame nor would expect a cop who shows up when there's already dozens of cops on scene an inside to somehow realize that everyone inside is just cowardly hiding around the corner doing nothing and be able to rush in and push past everyone.
With that said, there are a TON who deserve full blame.
All the cops who were apart of the first group who responded and arrived within minutes (I believe there were at least 8, maybe more).
Anyone in a command position.
Anyone who made any decision or directed anyone to wait and not engage.
Anyone who actively prevented someone who wanted to do something from doing so.
Any SWAT pretender who arrived for the purpose of acting and instead didn't and/or waited.
Anyone who knew what was happening and said or did nothing to facilitate a fast response.
Anyone who withheld information or later lied about the situation.
And it sounds like that is a very large number. But it's certainly not all of them.
But I digress. Your other point that if that many cops can respond in such a rural location, that location has way too many cops in the first place, is spot on. What exactly is the point of 400 cops showing up only for all of them to do nothing meaningful? I think the idiom of too many cooks in the kitchen probably applies here. Herd mentality too. So many people, nobody seems to be doing anything, therefore I don't need to do anything either.
I bet if instead only a few cops showed up and they knew nobody else was coming to help them, if only one of them had some balls, they wouldn't have waited for as long as they did...
In conclusion, a bunch should be fired for being cowards. A bunch fired for being incompetent. A bunch for being scumbags. And a bunch more for being unnecessary and pointless.