I don't think that they will eat them,
but will pester them to the point that they will retreat and and not open.
The key is to keep them fed enough to not want to pester.
I had one, and will never get another....pestered my zoa's to the point of not seeing them. Got rid of the peppermint, and they are doubling in size.
There are too many other types of shrimp to chance it.
However, if I had aiptasia in the tank it would have done a great job, I do not have it...Thank goodness, so no need to ever think about peppermints.