Bottom line is that EK has cancelled its flight. The underlying reason is not important. It is also not an EU (UK) carrier and thius, EC 261/2004 does not apply for flights originating outside the EU (UK). In the circumstances, I would take any reasonable itinerary back to the UK and sort the local costs afterwards with travel insurance or EK's customer service (which will likely be unavailing). My strongest advice is simply to get back to the UK soonest as the travel situation is tightening rather than loosening and that includes not only legal but practical commercial ones too.

Alternatively, the passenger is of course entitled to a full refund. If there is some routing into MAN at or about the cost of his EK ticket, he could take the refund and purchase a new ticket (recognizing that this means laying out the funds while the refund processes).