I imagine you would have been a little more understanding of a non-local diver accidentally missing the granny line. In the last two months I've had 6 charter dives here in SE FL and have noticed neither the Captain or the DM watching divers to make sure they are ok directly before they descend. I think both the diver and the Charter (Captain and DM) screwed up here.
It wouldn't have mattered in this case if they'd watched him or not. He did almost everything wrong on entry, including taking an action that would cause the crew to think he was correcting his mistake.
SeaLevelScuba:
Jim did not grab the granny line when he went into the water an was immediately swept out of reach,
I hate that term. It is not a line for grannys, it is a line for everyone, including big strong men. The proper term is tag line.
He didn't grab the tag line. When diving in current the first thing a diver does is grab the tag line. If the current is really strong, divers should grab the tag line as they enter the water. He missed the tag line, his first screw up.
SeaLevelScuba:
he was unable to swim against the current and drifted to the buoy behind the boat
He grabbed the current line. Exactly as he should have done. If the crew was watching him (I would have been in strong current) they would see the potential emergency was over. He is no longer drifting, he's now attached to the boat. He can now pull himself up the current line to the tag line and continue his dive. If the current is too strong, he can pull himself back to the boat and abort the dive. If the current is too strong for him to make it back to the boat, the crew can use the current line to pull him back to the boat.
SeaLevelScuba:
and decended down it to reunite on the bottom,
His second screw up. If he couldn't swim against the current a minute ago, why does he think he can now swim against it? True, sometimes the current isn't as strong at depth, but often it is. I certainly wouldn't bet my life the current would be significantly weaker at depth. He did.
SeaLevelScuba:
at some point he was blew off that buoy line and was drifting underwater not realizing how fast and where he was drifting.
His third screw up. He let go of the line in a strong current. His fourth screw up, he didn't immediately ascend to the surface.
When he did ascend, he did exactly as he should, he inflated his BC, dropped his weights and inflated his SMB.
While the crew may very well have made some mistakes (I wasn't there, so I don't know), the responsibility for him drifting to French Reef lies squarely with the diver, not the crew.