Letīs face it: An incident/accident mostly starts with a minor item developing to (maybe) a desaster.
A minor item could be a "RHS Line captain", not comfortable and not that proficient and more or less forced to this step.
Looking at the "high safety standards" of EZY ( Own declaration) there should be no need even to take any risk that is obviously avoidable! I know lotīs of experienced jet pilots waiting since month for their assessment!
It is just a matter of mangement planning and not a question of how good some of us are in changing seats and solve still different tasks!
Why support management misplanning in taking maybe a little higher risk of operation (flight safety)???
Some of the very "strong" pilots see it maybe even as some kind of challenge!? I am to old for being happy to display my abilities in the Left and Right seat just to solve management errors!
BTW, Lufthansa tried the same game some years ago, to force their Training Captains fly as RHS/FO duties on normal passenger flights. As far as I remember, this was even decided (against LH) at court.