I thought of the possibility that you had the chapter written already and the whale was a mere coincidence but I thought that was unlikely enough that I could proceed on the assumption that it was not the case.

I wouldn't say the coincidence was unlikely. The honeymoon location was carried over from canon and in such a setting killer whales are the obvious choice of food. They are more or less carnivorous dolphins. You cannot get too much higher on the "similar to humans and eat a lot of meat" criteria.

But you still have cause to be flattered. Great minds think alike and all that!