I was going to make a very similar comment to yours, but the more I thought about it the more the mammoth seems like a good test case.
It seems to me that we're just starting the testing & experimentation phase of resurrection technology. To be cautious I think we should start testing this new technology on extinct species that meet both of the following conditions:
(1) Are unlikely to escape captivity (ideally test species should be unable to survive outside specially designed enclosures).
(2) Are big, lumbering, and slow breeding. Even if such a species somehow escapes captivity (and manages to survive in the wild) we can still hunt them down and eliminate them.
So far as I know mammoths meet both of these conditions making them good test subjects for resurrection technology.
"... bringing [the mammoth] into an environment that it was not evolved to handle" - That's a feature, not a bug!