Considering the fact they have shot up a few vehicles without any shred of evidence Dorner was in them (or even the same color as the truck he was driving), they weren't trying to take him in alive... so they weren't trying to smoke him out. Why would he start the fire instead of just shooting himself, if his plan was to cash out and take him own life? Not a conspiracy theorist by any means, but they obviously didn't want him seeing a trial, for whatever reason. Maybe they just wanted him dead because he was attacking police and they were just exorcising some prejudice. The possibility exists that the fire was started accidentally, but I think it was more that they just wanted him dead.