Lets look at this a different way with a hypothetical.
Lets say a group of protesters is against a farmer harvesting tomatoes for whatever reason. The protesters trespass, they try to interfere with harvesting, they even go so far as to vandalize the farmers combines.
Now, does the farmer now have the right to run over this group of protesters with his pickup truck?
If you don't believe the whaling ship made a hard turn to starboard to ram the batboat, then there is no point in discussing. Because with this belief, then of course the whalers are not at fault for anything, the batboat purposely 'jumped' in front of them.
I don't see it that way. To me it appears the batboat was placing itself close, then the whaler purposely turned starboard to facilitate a ram. While the batboat 'greenies' are undoubtedly guilty of all sorts of maritime violations, including using speedboats to violate the 'spirit' of maritime rights of way, the whalers are guilty of using their vessel in a purposeful act of deadly force.