There's also at least one sprinkler keeping it wet.

This probably worked. Likely all that was needed was the sprinklers, but maybe they had the foil already on hand for some reason.

However, if the fire burned down the forest around them, the value of the property would be severely diminished. Years ago, my brother's cabin in California suffered that way. The cabin survived, but the forest was black. No one wants to buy a cabin in a hellscape and it takes many years for the forest to recover even a little.