Theres mixed feelings on this, some say yes and some say no. Peppermint shrimp eat aptasia, but rearely actually eat other anemones.
Alot of it has to do with where the snail actually came from. Aptasia is a warmer water species, and therfor only found in warmer waters. Only peps who come form this environment will eat aptasia, the cold water veriteies will not eat aptasia, another reason its very important to find out exaclty which genus your purchasing. This is just an example to provide some relativity and no factual bases here.
This thing will eat anything soft pretty much, nems, zoas and LPS. If you have any of those in your tank its very likely to have an apetite for one of these before it will ever go for aptasia. This is certainly a better safe than sorry scenerio. I would remove the thing and maybe find someone who has a FOWLR who can give it a good home, keep it in your sump / fuge or flush it.