An Accident
Whales weren’t known to be aggressive despite their colossal size. When the story broke, experts that weighed in on Michael’s hairy experience agreed that it was likely an accidental event.
Whales fed by sucking in vast amounts of microscopic plankton or small fish. In this case, the whale was most likely trying to feed on the school of sand lances nearby when Michael was inadvertently caught in the feeding vacuum its mouth created.