Fouling props with steel cable in antarctic waters could easily kill everyone on board the ship. Thats not the actions of fat hippies with a blubber fetish.
Look at the crew of wannabee bleeding hearts that took a combined world icebreaker response, aircraft, millions of dollars and a couple weeks to sort, trapping an ice breaker in the process. And they were doing nothing but being eco hippy tourists.
It is not the call of Sea to act as judge, jury and executioner. But it is most assueredly the right of a human to defend with deadly force against being stranded in antarctic waters to potentially die.
You leave out the time that the Sea Shepherds stopped their anti-whaling activities a couple of times to go to the rescue of a sailboat crew that was missing in the Antarctic and another time to join the Japanese whalers in a search for one of their men who fell overboard (not as a result of anything the anti-whalers did).
You probably should have watched the series...