The SPG flooding is probably not their fault. In fact it might not be flooded in the way you think. The only way water can get into the actual innards of the SPG, where the pressurized air goes, is if water gets into the regulator 1st stage. Because if there was a leak that would allow water in, there would have been a motherload of bubbles coming out one end of the HP hose or the other. I'm assuming you pressurized the regulator before getting in the water and didn't toss it in a rinse tank with no dust cap on, correct?
I don't know the details about how all SPGs are built, but if it really looks filled with water on the face, but when you pressurize it you don't hear a loud hiss, and if the 1st stage appears to be dry (look at the filter) then it's probably just a faulty SPG that leaked around the plastic lens. If you bought it there, they'll replace it.
The freeflow on a newly serviced reg is their fault.