Having been in the business of supplying the stuff... The term "tear gas" has been misused since WWll. There are two formulas used by law enforcement, CN and the stronger CS which are actually fine solid particulates. The original military delivery system was via generated smoke, thus the "gas" tag
Cold deployments disperses the powder by a pressure or popper charge. They rely on the suspect(s) to spread it up and around by traveling through it or attempting to cover/clean it up. Thus 'cold' deployment works better in confined areas. Another cold delivery more commonly recognised by its trade name is "Mace". Mace is simply CN or CS suspended in a pressurised liquid carrier.
Pyrotechnic deployments (nicknamed burners) disperse the particulates throughout an open area or building via generated smoke. The smoke also serves to reduce visual abilities. This also allows the use of additional smoke generators to increase the area of application without increasing the particulate saturation level.
My take is they didn't know if Dorner had a gas mask that could defeat the cold deployments. However, gas mask filters eventually do sustain a point of failure, so switching to "burners" to dramatically increase the level of particulate saturation in order to bring about such a failure was tactically correct and totally justified.
As to starting the fire... After the SLA shootout, a HUGE amount of R&D brought major changes to the manufacture, training and use of "burners". One thing is finite. The decision to deploy burners in any tactical situation (especially where a fire could be ignited) is a well discussed decision, often made far above the pay grades of the boots on the ground. So any inference the use of burners against Dorner was indiscriminate or to intentionally "fry the bad guy" is not only totally absurd, it's the product of a mind even more twisted than Dorner's.
Editor's Note: Jeffrey Sabatini blogs for Redlands-Loma Linda Patch from Redlands, Calif.