Clearly, if there is evidence that police started the fire intentionally, there should be consequences. But if police used a more aggressive gas cannister knowing it might start a fire, but would also be more likely to drive the suspect out of the cabin, I say fine.
The police did not napalm the building, the suspect had an opportunity to come out, he chose not to, fire or not.
It was a fire fight, if the police stationed a sniper and he had a shot at the suspect and took it, I would not be upset. Each moment this guy was not dead or in custody presented another moment where this guy could murder people.
I am not a big fan of police, I think they generally overstep their bounds and stomp of the rights of law abiding citizens. But this situation is why we have police. i wish they would spend MORE time dealing with seriously dangerous criminals than most of the nonsense they engage in. But I don't think this is the decision of the officers individually, more a bureacratic decision.