If we take your supposition as true for the sake of argument, what else would have to be true? I think specifically any boat smaller than 50' would then become a target. As there are many, many boats in the Mediterranean that are much smaller, and easily overwhelmed by Orcas, if your idea was accurate the report would include many events of people being lost and their boats being damaged.

Those things haven't appeared in the press. As a result I'd guess that something more specific about these boats, or maybe this place, that has them attacking.