It seems to me using a inert gas like nitrogen or co2 for the air assist would be the simplest and easiest thing to minimize flare-ups when cutting prone to catch fire materials. Perhaps it's not so simple, but I do know ULS has a computer controlled air assist dual system for my laser that allows using air, or inert gas. Perhaps that alone wouldn't be fool poof but with the possibility of fire on both sides of the material I can see where it would be hard to monitor the bottom side especially when the cutting table is likely filled will smoke while cutting. My laser has a battery powered thermal sensor in it. If the battery dies or gets weak the laser will not operate. I think the thermal sensor is mounted on the rear wall and will shut the laser down if it detects "excess" heat to prevent the laser from feeding the fire. However it seems to me by directing a stream of inert gas directly at the cut and using that to blow out the debris you are letting the laser cut the material but minimizing lingering flames by preventing or limiting the o2 needed to support the combustion.
What I get from Dan and Scotts comments is that if you make something that can detect "any" possible occurrences it is going to likely generate a lot of false alarms that will create more problems as far as productivity is concerned. My computer is 2 feet from the laser. I cannot go much farther away because ULS says to limit the USB cable to 6 feet max length. The port is about 1-1/2 feet from the right rear corner so by the time I come around the rear of the cabinet and to the front corner the 6 foot length is used up. So, I am always right there so to speak, and while I don't stand and watch every second the laser runs (depending on what is cutting) I am a one man show with our laser. We don't do near the volume that some of you do but I have over $60K invested in the laser and the small building we have it in. IMO the safeguards built into it hopefully would prevent a calamity but I think the first line of defense is me - the machine operator.
Universal Laser ILS 12.150D (48"x24") 135 watts total, with 60 watt and 75 watt laser cartridges. Class 4 Module (pass thru ability). Photograv 3.0, Corel X6, Adobe Design Standard CS4 Suite, Engrave Lab laser Version 8, Melco Single Head Comercial Embroidery Machine, The Magic Touch System with Oki C711WT printer, and Graphtec CE6000-60 plotter.