I'm not sure the math works out here. For most folks, those pumps would drain your pool in 1-2 hours max. So it's not like you can just set it and forget it. You'll have to hang around until the fire is literally right on you before you start spraying. At that point, you're going to have trouble breathing, it's going to be insanely hot, difficult to see, etc. Then, if anything goes wrong or you drain your pool and the fire hasn't passed yet, you've most likely lost the ability to evacuate. I think my wife and kids would rather have me around than the house.
After a little more research, it looks like firefighting resources recommend having 500-1000 gallons per minute (typically by employing 2+ hydrants) to fight a residential fire. You aren't getting anything close to that out of your pool unless you've got multiple pumps. And then you're draining your pool with maybe one lap around your entire house.