The sailor says they were heeling to Stb, Had they been on a Starboard tack, the bow of the powerboat would have cut them in half, rather than riding up onto the deck. The picture shows the mainsheet attachment still in the port tack position, despite the gooseneck end of the boom having broken off, supporting the port tack statement. Unfortunately for the sailboat's exposure to liability, being on a port tack on a J105, visibility under the boom would be at least partially obscured by the sail, so their opportunity to react to the presence of the other on a collision course would be reduced. An opportunity to quickly turn away was there, but they may not have had sufficient time to do so, due to that reduced visibility.
I am now thinking 75/25 on the powerboat.