I've been flying professionally for 21 years now and have to say I've never come across this attitude thankfully, most Captains I know of my age happily hand over most sectors these days to young enthusiastic First Officers and enjoy watching their confidence grow with each additional sector with whatever problems it might throw at them.
I guess you have to have confidence in yourself and your abilities to start off with but if all else fails a simple 'I have control' will suffice and a debrief on the ground as to why, simple surely. People make things much complicated than they need to be, who knows the First Officer in question may even buy you a beer in the hotel afterwards for being such a generous Captain.