I dont buy it either.
When BA sold GO to its managers it was clear from day 1 that GO would compete with BA (CX as it then was).
The question of a "no competition clause on established cross boarder routes" was then raised. The answer was that legally no such clause would be allowed by Regulators and was unenforceable in any event.
And so it was.............and thus GO then EASY flourished as BA (CX) declined.
So to suggest that such a clause would stand up here is at fours with the above.