To answer an earlier point, no, I am not sure it is a line captain's job to mentor/train/instruct new pilots. Our line trainers have to do a CRM facilitators course, ground instructional training course and a fair amount of flying instructional training to do that: you think it's fine for me to do this without any of that?
The practical outcome of this approach is what tends to happen a little anyway, although less and less as all the dinosaurs die out. Line captains showing pilots fresh out of their line check "better" or "other" ways to do things. Having been on the receiving end of this type of thing I can report it is just a pain in the ar$e. You are just trying to get on with what you have been instructed to do when you are shown another way to do it along with an unwanted and sometimes plain wrong lecture. These guys are not idiots; they can see how you think and what you do and say; they will pick it up by osmosis. And if they don't, it's because the way I do isn't that great, or they don't get it, in which case they will have it beaten into them on recurrent line training.
My point about the gradient thing is that the more you adopt a mentor/instructor role and they a student/apprentice one, the steeper the cockpit gradient becomes between them and you, and, I believe, the more inhibited they will be in making a verbal or physical intervention if required. And if the gossip I reported is true then these matters are key because it looks like the Cougar, ETAP and this one all had this as a contributory factor.