@johndiver999 nailed it on the regulator sweep issue. It just isn't applicable in this scenario. The victim went over the edge of a 5 m dropoff. If a sweep (or what have you) is going to work anywhere, it should work in 5 m.
A friend of mine used to say opinions are like a certain bodily orifice: Everyone's got one and they all stink. With that in mind, here's my take and what I tell OW students:
1. Inflate your BCD before your toes touch water on a beach entry. You fall over, you float.
2 I'll let you be ankle deep to rinse the spit/defog out of your mask, but any deeper the mask is on the face so you can at least see if you trip. I'm not a stickler for this, but I encourage them not to take the mask off their face until their feet are firmly on dry land again.
3. Snorkel should be in the mouth. If you fall over face up, you can spit out the snorkel and inhale the air your face is in. Fall over face down, use the snorkel. A reg is unnecessary IF YOUR BCD IS INFLATED.
4. Do not try to put on fins until you're in mid-torso depth of water. Same for fin removal, don't go shallow to do it. (Keeping in mind we're not doing surf entries, where things could be a bit different.) People futzing with fins in shallow water (or worse, sitting down in the shallows to put them on or take them off) get rolled by waves or ship wakes where we dive.
Earlier somebody mentioned that a reg on a necklace implies primary donate. Not necessarily: A DM I work with a lot has her primary on a necklace, so it never goes anywhere. She does secondary donate. To be honest, I'm not sure why this isn't routine practice other than it's another expense for the LDS.
A different person mentioned PADI being fine with primary or secondary donate. On the one hand, that's true generally. They do not prescribe a particular method of sharing air. On the other hand, post-COVID I'm not so sure they'd approve of a reg going from one diver's mouth to another diver's mouth without a sanitizer step between. (They changed a lot of things during COVID, and I just don't know if they returned this one to "normal" or not since early in the pandemic. Not a tech instructor, so I don't know what they do for tech classes.)
I can see where our tech diver in doubles might have had more trouble getting his kit off, especially with a Hogarthian rig and thus no quick releases at the shoulder. *IF* he was wearing doubles and a Hogarthian rig.....
Last, a person commented that they dove without weights and were head just below the surface, snorkel above, with a full tank. This doesn't make sense to me. If the head is fully submerged, that implies the diver is negatively buoyant (in that moment anyway). They shouldn't be able to hold that depth without kicking. If you're hovering with just the tip of the snorkel above water with a full tank, how do maintain a safety stop with an empty tank? You can compensate with lungs for a bit, but losing 60 or 70 cubic feet of air from a tank is more than my lung volume can compensate. Call me confused on this. Maybe they didn't mean the whole head below the surface, but just the bits necessary for breathing?