Gouli: In military ops crew roles are defined. There isn't mixing and matching of roles, for instance a Seaking Observer/Radar Op can't do the co-pilots or winchman's job just because someone is more senior or less experienced.
Mil aviators are just as used to working with different crew members as civ ones. Obviously the smaller the community the more you get to know people but it's really a lot more standard than you've inferred here.
I believe that the map shown could be interpreted as an IFR let down / company route when it's not intended as such but maritime helicopter operators are used to letting down in such situations over water, using the radar as the primary tool. In my experience this has been done by a trained radar operator who monitors the descent and other PM duties as normal. Not sure I'd feel that comfortable with a pilot with no training on radars (as has been inferred by some) doing that function.