I would start by looking through Hays Travel initial docs and finding the airline PNR. Even if its cancelled, you can call EK and ask them to tell you why it was cancelled. It's rare even if a flight is oversold to have a flight cancelled in advance, usually happens if there is a seat issue on the flight or something but usually EK will upgrade or manage that at the desk as you may get a no show.

Since it was a Man flight and cancelled within 14 days, he may be entitled to EU261 but needs to get some more info as to cause of cancellation