Very good!
Divers in black wet suits on the surface can easily
be mistaken for seals.
so can kyakers.
They will spit you out but you will not
always escape un-harmed.
Seals aren't on the the humpback's menu. They feed on krill up to smaller fish like mackerel. Maybe it mistook the kayaker for an orca or shark and was just trying to defend itself?