Your thinking would be correct if the air supply was critically low. Even if I was at zero psi in the main tank,I personally had a 13 cu-ft pony (if I recall correctly) to make the ascent - so there was no need to rush to the surface, I had the luxury of coming up slowly and clearing the very small deco penalty by the time I reached 44 ft or so.
It took me only about 100 psi to ascent from about 100 and get to 44 ft (where the deco cleared) and since I was calm, relaxed and was not exerting myself, my air demand would remain low giving me more than enough air to continue to ascend in a controlled manner and do a safety stop - without running out or using the pony.
So in this situation, your safety would not be enhanced by rushing to the 10 ft deco stop ASAP- Obviously a diver has to make some decisions if they are at 100 ft with less air than they would like and no pony bottle.
The video shows that this particular ascent was trivial and simple and required very little air. That demonstration may give others the confidence to not rush to the surface unnecessarily (if they screw up).
Of course it is more important to have something to breathe than to worry about the consequences of violating a decompression ceiling, but a diver has to make reasonable decisions, once they put themselves in that type of undesirable situation.
Again, I am not advocating for recreational divers to push the NDL or to start their ascents with too little air.
Also. one of the things I dislike about the discussions on this forum has to deal with people bragging about how little air they use. My personal SAC is not low at all. I am over 200 lbs and not young and use a good bit of air. I have found out long ago that trying to use less gas than is needed will give me headaches and it is actually quite dangerous for a variety of reasons.
So one of the things that divers should be able to discern from the video is that if you start the ascent calm and rested and not sucking wind, and you don't kick up, but "drift" upward using the BC and breath control, you can remain motionless and this may keep your air use to a low level - at least for the few minutes it takes to get a lot closer to the surface.
So even if you had no pony bottle, had 250 psi in your 80 ft tank, no buddy and a short deco, putting a puff of air in the BC and trying very hard to relax and watch the computer would probably be safer than swimming really hard and trying to get to 20 feet in 60 seconds or something. It is really important that you not use the large quad muscles and keep your arms calm if you have to make a low on air ascent (and want to preserve the air supply). This sort of situation would be a true EMERGENCY, but that means it is more important that your response to it needs to be appropriate.
For me personally, I would be pretty comfortable swimming to the surface from 40 ft depth with no air in an emergency. Much deeper than that, my comfort level drops a lot - so anything 60 feet or deeper will cause me to carry a pony bottle - even when diving with a buddy.
In general, I do some diving in 20 feet and carry no pony bottle and everything else is 50 - 60 feet (or more) - so I always have a pony.
