Exactly - they look like they are itching themselves on the point of the rudder. Maybe there is some infection near their blowhole that they are trying to scratch. Take some bio samples from the rudders for analysis.

The animal does not seen disoriented, just exploring the object. I seems play behavior

If I'm not wrong, the giant worm Crassicauda does not affect orcas, but can attack false killer whales and relatives, so is not an impossible hypothese

I recommend probiotics.