Boy, when I screw up, I do it big time:
Since water is immiscible in acetone it won't affect the flash point; the water would just boil away. My point was that the claim of RxP being acetone doesn't "hold water." (Pun intended)
Take it from an ex-chemist: water is completely miscible in acetone in all proportions. However, putting acetone-water in gasoline probably wouldn't be a good idea.