The simple answer might be the right one, it just felt bad for the seal. Nobody really knows how intelligent humpback whales are.
It is also why I feel commercial whaling (or in Japan's case "scientific research") is such a horrific thing to do.
My point is, it's not wrong to apply different standards for different animals. GP says they feel whaling is wrong because they relate more to whales than they do with cows or pigs. If GP sees news articles on how cows are actively saving other helpless animals from getting hunted, maybe they'll start applying similar standards to cows too. You may find this illogical and annoying, but bringing up cows and pigs in this way is not constructive in my opinion.