Mike Nelson always had problems with hose cutting divers in Sea Hunt episodes. So it's pretty obvious one of the "customers" was really an enemy agent who snuck up and cut his hose while he was busy tending to the real customers. And it's worth noting that Mike often went for the surface when this happend.
But in all seriousness, I agree with the DM's actrions in the other story. I think an ascent from 50 ft to the surface on the octo makes sense in that situation, especially without a buddy you trust. It's a sure thing as even with a ruptured hose your gas will last long enough for a normal ascent. And it does not sound like he was exactly swarmed with willing donors even though he had an obvious problem, which is another indicator that as a DM you are basically solo.
But in all seriousness, I agree with the DM's actrions in the other story. I think an ascent from 50 ft to the surface on the octo makes sense in that situation, especially without a buddy you trust. It's a sure thing as even with a ruptured hose your gas will last long enough for a normal ascent. And it does not sound like he was exactly swarmed with willing donors even though he had an obvious problem, which is another indicator that as a DM you are basically solo.