Depends.
Is the plastic in those water bottles, soluble in gasoline?
Generally plastic bottles are made from PET or PETE, a polyester based compound, or a polyethylene, either HDPE or LDPE. Some are made of Styrene...none of which would I hold in my hand while filled with gasoline in proximity to a flame. But hey...I think it's a good idea for antifa punks to try.
LDPE becomes soft, pliable and weakened when filled with gasoline.
It dissolves, slowly.
Very easily punctured but not likely to break on impact.
Yes, would make a very good “slow” fuse as the fire melts/releases the gasoline.
With “slow” being relative.