well in this case then when you point the gun straight down or straight up the tube would still be submerged... but ive never noticed anything shooting paintball guns straight in the air. maybe its just bc the tank is so small.
The paint ball systems are designed to "handle" the liquid withdraw and the expansion of the liquid Co2 to gas. A standard industrial/food grade Co2 regulators that the majority of us use are not designed for liquid withdraw.
The issue is not the regulator, it has safety features build in to release the energy from the liquid changing to a gas. If the liquid gets down stream of the regulator most of the systems have part in place that are not equipped to manage the pressure increase. The potential for a catastrophic failure at this point is quite high.
The point I'm trying to make is that many of us have our kegorator/keezer in areas where our family and friends frequent, "it" may never happen but "if" it did and the fix was that easy I know how I would feel.
If you buy a standard co2 tank for paintball it probably does not have an anti siphon tube in it. You need to have an air smith install one. In a paintball marker the valve that allows co2 to enter is only open for a split second so the amount of liquid co2 is minimal. Some markers even have chambers built into them where the liquid can expand before entering.