So, what's your game plan in a low air situation--that leads to an OOA surface situation when you're floating on the surface for (up to) several hours in a 2 to 5' choppy sea??........Please don't tell me you're that good of a breather when your head constantly remains slightly above the water line in that kind of a sea...
No. As my weight is correct and my kit suitable for the job i simply inflate my wing, float and wait. 2-5 foot seas really arent a lot at all. If the seas are 5ft an 8" plastic tube isnt going to help you at all.
Its far from uncommon to have to drift around on the surface waiting for the boat to pick up the other divers. 30+ minutes is quite common if its a busy day. Not one person carries a PADI-tube, the swell height of 2-3m is common, force 4-5 winds are common and despite that not one person has the slightest difficulty in staying on the surface and breathing. In all the missing diver incidents from the last few years here that lasted several hours in conditions the same or worse not one of the divers had a snorkel. And yet amazingly they were all fine and not one person has even suggested its needed.
Snorkels on the surface are a diver looking for an excuse to make up for his incorrect choice of kit or weighting. They are of no use in extreme conditions and the only conditions you could possibly use one are the same conditions that you dont need one in anyway.