They aren't going to do that because of how the public would perceive it. I know little of this incident beyond what bits I've gotten from the news, but aren't these hunts specifically sanctioned by the Japanese government? If that's the case, it's not like these whalers are just rogue criminals--they're within the laws of their country. If Japan is in defiance of international agreements by sanctioning their hunting, then the appropriate course is to engage Japan itself diplomatically.

Attacking someone's ship, particularly in an environment where such attacks will jeopardize lives, is criminal. The Powers That Be should act accordingly. Personally, I think it would be appropriate (and amusing) if there was a warship around to put a 5-inch shell across the Sea Shepherd's bow when they go to ram.

We've had protester and whaling ships damaged in a collision while the protesters were trying to block the whalers, protesters knocked overboard whilst intentionally interposing themselves between whales and harpoon guns, and protesters throwing nets into props and tossing warning flares about. Given the stories that have come out of that expedition the past several weeks, I'd say it was a reasonable assumption that the protestors had a hand in a fire. Whether that was true or not, fact is that their activities are extremely dangerous, both to the whalers and themselves.

Oh, and Creac: According to the articles I've read, it was the Greenpeace ship Arctic Sunrise that was involved in the collision with the Nisshin Maru--though each claims the other did the ramming. (Though one might wonder about that, given that the whalers are there for the whales and the protesters are there for the whalers.)

The whole thing's a mess. Seems to me it would be a sight smarter if the protesters would spend more time lobbying world governments to put pressure on Japan to stop the whaling.