Malrim, you beat me to it!
Silver could you provide regulatory reference that supports you statement about employment with a different airline after MPL and IOE.
I found this, which is from CARS and is the same iin JAA FCL, EASA 17B and ICAO PANS TRG.
Approval for a MPL(A) training course shall only be given to a FTO of a CAR-OPS 1 operator or a FTO having a specific approved arrangement with a CAR-OPS 1 operator. The licence shall be restricted to that specified operator until completion of the airline operator’s conversion course in accordance with CAR-OPS 1 Subpart N.
As I read it, Alpha(UAE) are offering 40 Sectors, which is the Operators Conversion Course, on completion the MPL holder can then legally move to another Operator should they want or need to!