I dont agree with the NOC policy as it stands, but I will say that this is similar to a "no competition" clause in a majority of international contracts, with some of these clauses even being for a period of 5 years or more.

If you sign a contract saying you will not work in the Gulf, or Qatar, with a competitor for 5 years after your contract, it is the same only we are dumb enough to sign our consent on this before we come :)

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"Diplomacy is the art of saying 'Nice doggie' until you can find a rock - Will Rogers"