I agree with kwinter that creating a second victim is generally discouraged, no matter how brave doing so may be. Seeing as how this is the A/I Forum and not Passings, it’s quite appropriate to note that being braver than your skillset can support can end with you being just as dead as your buddy and just because you think you’ll have enough time to bail if your efforts fail…you might have guessed wrong about the margin for error.
But the ‘don’t create two victims’ rule is taught to minimally-trained recreational divers for diving with what's often going to be an insta-buddy. Even the blandest PADI rescue instructor will caveat the 'don't just make it a double body recovery' admonishment with a reference to something like 'if you're diving with your [insert family member here], of course you're going to do what you feel you have to do....' In this context, you're dealing with professional divers whose entire training and relationship to each other is based around shared dedication to an ideal, that the only thing more important than their teammates is the mission. The untrapped diver’s efforts are understandable and laudable in that context, whereas we’d not praise (or at least not unequivocally praise) the bravery of a tourist who got him/herself killed trying to rescue an instabuddy. In fact, the only thing about this that really surprised me was that the trapped diver didn’t cut his tether and free his over-determined swim buddy when he realized he wasn’t going to make it. But perhaps unconsciousness or panic got him before he could make that choice; we’ll never know.
There are lessons here about what not to do if you’re not a military or rescue diver. If you are one, this is more a lesson in how badly things can go sideways to the point to where your choices are either do a dive that might get you killed, or, disobey a direct and likely lawful order from some moron who doesn’t belong in the position they hold. Respect to those who place themselves in such a potentially untenable position out of a desire to serve.