"All Captains are qualified to be First Officers"
About 12 sectors as PICUS (In Command, under supervision) with a Training Captain but occupying his accustomed (right) seat.
Not so, once they become a Captain they cannot carry out their duties from the right seat unless their company trains them to do so.
My previous company had a policy of training their Captains to fly from the right seat 6 months after their command, which gave them more flexibility with Captains on standby who were checked out in the right seat and so could replace a First Officer as well as a Captain.
Those who had just become Captains though could not occupy this seat.
A First Officer may not occupy the left seat unless on a command course, in my airline that invoves:
5 Sim Details (familiarisation with LHS, LHS base check, LHS IRR, LHS AWOPS, Loss of all engines)
16 Sectors Route Training in the LHS, followed by a Route Check over 2 sectors by a Management Pilot
Every airline does it differently, but I guess this pilot is on his command route training. With any luck his 4th stripe will follow within a few weeks!
I used to love the smell of Jet-A in the morning...