I keep snails and hermits with my snowflake. I have never seen him go after any of them before, but , that doesn't mean he doesn't when I am not looking.
I haven't noticed that I have any fewer snails or hermits either. I think he would be less likely to go after them if you keep him well fed.
The only living things I have ever seen mine go after are my fingers. On that note from personal experience I can tell you that small Snow flakes do not have much in the way of teeth (unlike Undulated morays
).