The only person who can't fire a ranged weapon is someone without a
BS score.
If the turret allows anyone nearby to fire it, and they have a
BS stat they can fire it, even if they don't have a ranged weapon on them, as they won't be using their splinter pistol or whatever anyway
There are a fair few
CC oriented models that have rocking
BS stats
Incubi are the same way, for example. Tne only ranged weapon they can access autohits