To the OP :
Most probably (if no brag from your friend) that was a very short bounce at 50 meters/165 feet, making for a few minutes of deco stops. Dive computers, and dive tables for deco diving, allow air dives deeper than 39 meters/130 feet (unlike PADI tables). Thanks to his/her dive computer, and while having (hopefully) your friend staying close and at the same depth than him/her at any moment, the instructor took care (hopefully) of the air consumption, dive profile and deco stops for both divers. Unless your friend had his/her own dive computer ; you didn't tell much.
For me, judging what they did as really hazardous, or not, depends on the sea conditions that prevailed (for instance, narcosis hits more quickly in cold, murky water than in warm, clear water) ; on the certification, experience (you gave no clue about them), aquatic gifts, SAC (a short bounce to 50 meters with an AL80 is doable with a low SAC), fitness and self-control, of your friend and of the instructor ; and on local laws, that have to be respected. But personally I would never allow such a dive to divers not specifically trained and certified for this depth, unless it's part of their regular training with a recognized agency.
To others :
In my country, bounce air dives in open water down to 50-60 meters/165-200 feet on a single tank (usually a 15 liters/120 cubic feet, with no bailout and no stage) are allowed by law/diving federation rules and are routinely done (by adequately trained and certified leisure divers, ie CMAS ***, not by beginners !) ; while such dives are frowned upon, or even judged suicidal, in some other countries. The same can be said of the possibility of freely buying and owning firearms (forbidden in my country). Cultures, laws, practices, and definitions of what is overly dangerous and what is not, are not the same everywhere ; and they change in time.
With all due respect, Scubaboard often sounds very North-American. But even in North America, I guess that in the old days (till the end of the seventies) many experienced divers were using Navy tables and doing single-tank deco air dives down to 200 feet ; then came the agencies calling themselves "recreational" and making almost everyone believe, thanks to intensive advertising, that so-called "recreational" no-deco diving, down to 130 feet maximum, was the only way ; and then came the "tech" agencies.