Obviously this a “don’t try this at home” kind of thing, but it is educational to look at what is going on. On one hand divers are taught that exceeding limits far less than the OP describes should never be done. On the other, people do stuff like this all the time. No wonder new divers are confused.
There is a lot of human variability where decompression sickness and oxygen toxicity are concerned. Same for Nitrogen Narcosis, but many believe including me that repeated short-term exposure increases tolerance. There are also different “acceptable occurrence” values. Zero risk is easy, never go underwater.
Hundreds, and possibly thousands, of US Navy First Class Diver candidates have made simulated dives in a chamber to 285' on air. These dives were in very controlled conditions but, if the mission required it, divers were expected and did make dives in open sea using surface-supplied Mark V deep sea gear… a much more controlled situation than in Scuba.
The Navy Experimental Diving Unit has run across a few people who have not developed DCS symptoms nearly as readily as most of their other human test subjects. There just isn’t enough data to know what percentage of Navy divers they represent, what happens to their tolerance with age and physical condition, or if the lack of apparent symptoms had long-term detrimental effects compared to their peers. That some people are less likely to develop DCS symptoms is undeniable… and unpredictable.
Same with oxygen toxicity. The July 1963 US Navy Diving Manual, Part 2, Page 55 states:
DEPTH EFFECT
(4) Oxygen toxicity limits the safe depth of operation for closed-circuit (pure oxygen) scuba. Extensive operations are hazardous below 30'…
(That’s about 2.0 ATA working, not emergency)
The Navy has adopted more conservative Oxygen exposure limits in the last couple of decades. It isn’t unusual for Navy combat swimmers (SEALs and the UDT before them) to exceed 60' under very stressful conditions without OxTox symptoms, even though it far exceeds the depth considered safe.
What is Safe?
As you can see, the answer is a pretty squishy and highly variable, but then what about diving isn’t besides maybe air embolism? Deeper, longer, and worsening sea conditions all compromise diving safety. Skill, equipment, and experience can offset SOME of that risk. What the OP describes is certainly on the less-safe end of the spectrum, but not impossible or certain death.
Does it Make Sense?
That is a value judgment. Apparently these divers think so… they must really like fish. Every diver must ask themselves what risk is acceptable. It is the responsibility of each diver to understand those risks, how to mitigate them, and gain sufficient experience. It really doesn’t matter if it is learning not to embolize yourself in water shallow enough to stand up in or performing
saturation dives at 1000'+ in Sea State 6.