My 2 cents
It looks very unprofessional for a pilot to be chatting to CC or drinking or eating in flight. If you care what your customer thinks you wouldnt do it
If you want to socialise why not open the FD door and stand by the exit to speak to disembarking passengers. Might improve image and get happy punters
The need to exercise is a red herring. Pilots do not not seem to have a raised thromboembolic risk - reason unclear.