They should have just removed some back spikes as an identification. Ive seen them do this with fish and other water life. They find a section of the fish that routinely gets damaged yet they are fine. They then notch that section with a marker. So if the side fin has 2 triangles cut out, and the top fin has 1, that is "Bill the fish" and bill could really care less since the edges that they notched are pretty ragged anyway.
But no one docks/notches a prehensile tail... Thats about as dumb as removing a usable claw (vs a dewclaw) on a mammal.