Because Sigfreid and Roy domesticated Montecore, he will be euthanized.
That's not true. According to every article I have read, the tiger will NOT be killed.

And, just a note, tigers are never "domesticated". Some of them might be "tame", like Montecore, but they are never "domesticated." It takes many thousands of generations to domesticate a species, such as dogs, cows, etc. Taming one animal does not a domestic species make.