So, should this guy be denied his C card? He seemed to be a safe diver who had a true love of the sport, and for OW isn't that good enough?
Consider the scenario I posited which
could have happened yesterday.
You drop down to the bottom. You have horrid buoyancy skills and crash into the bottom The boat driver (me, in this case) has skillfully anchored about 10' off the reef, in a bottom comprised of MUD.
You hit the mud and instantly create a huge mushroom cloud of silt. There is no bottom current. The silt cloud slowly expands, obsuring the anchor line. You are now in zero visability.
You can probably swim out of this to get to the reef, and see it. Since the reef is hard bottom, while you will damage it by kicking it incessantly, that's ok - its just a reef, right?
Ok, so now we're at turn pressure and about to go back to the line and ascend. Except for one problem - we can't see the line. Its SOMEWHERE in that huge silt cloud, but you can't see it. Where is it?
Hmmmm.....
Let's see which of the bad choices we'd like here:
1. Fumble around trying to find the line by TOUCH, creating even MORE silt, and reducing the odds you'll find it, until we run out of air and drown or are forced to do a CESA, perhaps getting an iron pony ride.
2. Make a free ascent. Not a problem if you have decent buoyancy skills, but oops - you don't, which is why the silt cloud exists in the first place. So now you attempt the ascent, and it gets out of control. You rocket to the surface, completely unable to do your 15' stop, and subsequently wind up possibly getting that iron pony ride again.
The possibility of a free ascent must always be something you can accomplish. While you shouldn't NEED to make one most of the time, you always may be in a situation where you NEED to make one. And don't even start with "just shoot a bag" - do you think someone who can't hold position in the water column could manage to shoot a bag without really serious trouble? I don't!
IMHO the OW class requirement for buoyancy control is simply addressed. In open water, the diver must be able to, beginning from a dead-stop (not moving!) while neutral, make a free ascent to the surface, not exceeding the safe ascent rate (30ft/min) and, in a controlled manner, stopping and holding position between 10-20' for the required three minutes.
If you can manage that, you have "passable" buoyancy control for open water diving. If you cannot, you do not. Period.
(You can "cheat" on such a skill using some fin motion, but you'll never manage it if you can't get darn close to being neutral.)