As this thread is about nobody we know, I think it's OK to hijack it a bit.
In my line of work, there is a subset of folks who know just enough about how one thing works and therefore think they fully understand how all things work. It's not that what they know is wrong, it's just that it's not very complete or nuanced. They own a hammer and everything looks like a nail.
By way of example, I ran a call at an ethnic restaurant the beginning of this summer. It was a pleasant day, in the low 80s. The freezer was in a kitchen that was 95*, with the condensing unit sitting on top of the box where the temperature was over 100*. The freezer was packed with food from floor to ceiling, back of the box all the way to the door. The system was low on refrigerant. I added a couple of pounds of gas, and told the owner that he'd need to move the food in order to find and fix the leak, and that he really should consider moving the condensing unit outside. He was having none of it - the box was "fixed".
A week later, he called back. The temperature was over 90* outside now, and the kitchen was sweltering. The temperature on top of the box was hotter than the surface of the sun. I sent Right-Hand Man Brad on the call, and he found the head pressure in the system over 400 psi (normal is 250, and the burst pressure of the piping is about 450 psi). The owner knew exactly what the problem was - the system needed gas. I had told him there was a slow leak, and he just KNEW it was low on gas. The fact that it was not (in point of fact) low on gas was not computing with him. He knew what the issue was. The box was warm - just like it had been when it was low on gas. Ergo: the system had to be low on gas. Correlation equaled causation. This nail required a hammer.
I had to go over there to confirm the diagnosis, because he didn't trust Brad. We both told him that he'd need to cool down the kitchen or move the condenser outside, and that the box needed to be unloaded if he wanted a leak check. He refused to accept any of this. I told him that if he wanted a second (third?) opinion, I wouldn't mind - but we were done until he took the advice. We both left.
A week later, his wife called and asked that I (not Brad) come over and add gas to the system. I declined the request.
The point of this long/boring story?
We're a lot like that here. Somebody posts something that seems like a good idea (Blazecut, in this instance), and it becomes the orthodoxy. If anybody posts a picture of a burned car, we respond in unison (like a responsive reading in Church), "it could have been saved with a Blazecut". It becomes what you say in a situation like that, akin to "I'm sorry for your loss" at a wake, or "I'm so very happy for you" at a wedding. We don't even really think about what we're saying, we just want to say the right thing. "You're probably relieved" or"I'll give you 6 months" doesn't seem like the right thing to say, even if it's true. Nobody likes to think about their car burning, or how hard it might be to stop it.
The fire thing is a lot like the funeral/wedding thing. We don't know that a Blazecut could have saved it, but we wanna' say something meaningful. As Danny pointed out, a Blazecut has a thimbleful of retardant in the tube. There are no nozzles of any kind, so when the tube melts it might spray exactly where it's needed, but then again it might not. The one thing that is for sure is that there has to be a flame for the tube to melt at all, so the fire is going to be blazing away before it discharges.
There's nothing wrong with the idea - a passive system seems like it might be a good thing to have. But we have zero data to prove that a Blazecut will always be enough, or that it could have or would have saved this particular car in this particular fire. Suggesting it would have saved it is just the thing we say when we don't know what else to say, and when we aren't thinking very hard about all of the possible outcomes.
Freezers get warm because they are low on refrigerant. Blazecut would have saved it. 60% of the time, it works every time.
I call this the "Folklore and Common Knowledge" effect. It's shorthand of the kind of apocryphal tale that sounds like it ought to be true, but nobody has borne witness to the facts being relayed. I'm lumping plastic fuel filters in the engine compartment in this same category. We've been hearing for years that it's the sin unto death - but I know of nobody who's actually seen a car that burnt as a result of one. It's probably not a great idea to have one in there, but it's not likely to spontaneously combust.
To introduce my own bias to the discussion - I'd bet that 99% of these cars burn because they sneeze back through the carbs and soak an air-filter element with fuel. At that point, the car is one backfire away from lighting the element, and setting off a campfire. This has nearly happened to me twice, so at least I've seen it. In such a situation, a Blazecut may spray just the perfect amount of retardant right on the air-filter and extinguish the fire (hooray!). But it might just as easily spray it's thimbleful of retardant in a different direction, where the cooling fan sucks it out of the engine compartment and discharges it out the bottom of the engine. At that point - you've already spent your nickle and no candy fell out of the machine. It might still be worth putting the nickle in the slot, but I'd have a backup plan if it didn't work.
I'm not saying a Blazecut doesn't work - as I said, they seem like an OK idea in the hypothetical abstract. But as far as I know nobody has actually seen one that saved a car, and I'm asking that we stop repeating stuff that sounds like it ought to be true if we don't (in fact) know it to be true.
That's not "settled science" that's "Folklore and Common Knowledge".