I'm not sure if that is correct. I just watched it again. I saw the skipper twice pick up his life sling and put it back down. It looked like he was shouting something to the MOBs. I'm guessing he felt he could not take his boat out of the protection of the sea wall and the MOB's were too far for him to throw his sling. I also saw the guy on deck pick up what looked like a raft or board off of the deck and put that back down. They were obviously trying to work through the situation. Then the power boat pulled up along side and that is when the sail boat motored off... it did not look like he abandoned his crew to me... and he did come right back. It looked like he dropped off some of his crew. Maybe someone was injured? If that is the case the skipper was basically doing triage and once he knew his MOB situation was in better hands than he could provide he cared for his remaining crew.
Also there was obviously another boat on seen... someone was working the video camera. (?)
Hard to really know if you weren't there.