In my opinion, the reef hook shown above is dangerous because of the snap attachment. Under a heavy load caused by a current, this snap can become difficult, if not impossible, to release from a D-ring...
I wondered the same thing and asked my neighbor when he showed it to me. He said it wasn’t difficult to pull yourself against the currents he experienced to unhook either end. Someone with compromised hand function might have a problem but would also have a hard time removing the reef end.
If you really want a hook that is easy to release under a strain, I haven’t found a better solution than a snap shackle. This photo is of one on my weightbelt that replaced a brass suicide snap hook recently.
You can get several different stainless steel snap shackle sizes and styles from these guys for 5-$15: Shackle Hardware
They are usually much more expensive at a marine supply. The lanyard to assist pulling the pin is added separately, but required for divers. Some divers like a monkey-fist (decorative knot) on the end but I find it can snag and accidently open. The lanyard can be much simpler than the one in the photo and work just fine.