I have a Tiger Pistol paired with a Yellow Watchman in my 24G Aquapod. They've shared the tank with a Peppermint Shrimp for over a year, and an Emerald Crab for a month or two. I don't think he's ever killed any hermits either, and I only have Blue Legs. He will snap at them if they get close to the burrow though.
I'd say it depends on both the shrimp, the presence of a paired goby, and the layout of the rockwork. The reason I consider the presence of a paired goby is that my pistol seems to be very dependent on signals from the watchman, and the goby shoos him back into the burrow if the peppermint or the algae blenny starts coming close.