I don't know about your military mindset, P1090, but in my military experience, CDE (Collateral Damage Estimation) is huge.
Dropping munitions on a dwelling without verifying the absence of non-targets is only done in extremis. This case was not an in extremis case. All the officers had to do was pull their cordon back out of effective range from the cabin, and wait behind cover.
They were hardly going to take overwhelming, long range fire from one gunman.
What they did was not justifiable. Again, I really don't care about Dorner. I do care about precedent.