Yes, the Peppermint shrimp is reef safe. And why not rely on a shrimp to control the aptasia?? The shrimp will help prevent them from comming back and spreading. I think it is the safest way of getting rid of them rather than using some type of supplement or chemical.
Now, however, with the peppermint shrimp I hear that it is hit and miss to which the shrimp will actually eat them.
I guess, this is my recomendation, and it worked for me. Since you want to get a peppermint shrimp the first place, I would give it a whirl.