That's a slightly different case. It's not the stealing of the method that Teller objects to - it's the stealing of the act. The aesthetic, the script of the performance. Which I think is fair - it's an exceptionally artistic act, and performing it as one's own is rather like performing a song written by someone else without crediting them.

I don't think magical methods can be copyright. At best, they can be patented. It's not even clear that the copycat act uses the same method! But that's besides the point completely.