That's an interesting situation. The decision to attend had nothing to do with the RNLI so they're out of the debate straight away. Their only input will have been to report on the state of the boat and crew to the CG.
I say interesting, because someone always gets the blame for things that go wrong. If these terwats had been drowned, then you can rest assured that their next of kin wouldn't have chalked it up to bad luck/stupidity and a witchhunt would have been started. "Who in charge knew that these poor inexperienced men were out there in the new boat that Tommy had got for Christmas, his last Christmas with Tammy...?"
I can think of a shout where a drunk had decided to swim out to sea and die. The RNLI were tasked to find him and rescue him. They found him (well out to sea and going strong) but he refused to be rescued. In fact, he was a big lad and threatened to knock the teeth from the first man to touch him. So they had to sit with him for an hour or so until the cold dampened his fighting spirit and he agreed to be recovered. Crazy? Yup, but what can they do once the situation is reported?
The police have some powers in situations like this (AFAIK) but the rescue services don't - they just have to keep trying to rescue.