It would be funny if it wasn't so sad!
It is such an ill conceived policy one doesn't really know where to begin.
The irony to me is EK are making a damning statement about themselves and don't have the self awareness to realise it.
In the time these Captains have been at EK, they have been following company procedures and policies, flying a wide body airplane from the same manufacturer as the newer airplane in question and have been through the gauntlet of EK upgrade. If after all that, the airline thinks they are not capable of completing a conversion successfully, then I would say the company has failed miserably in the professional development of these pilots.
It is simply ridiculous.