200 is 93°C - not too much above the VW standard 90°.
A radiator flush out??? What does he put in the radiator - VW approved coolant, or boring old tap (faucet) water? If the latter, and if he lives in a hard water area, the radiator will become knackered after a few years. I don't suppose he uses antifreeze - lol - and ordinary water has a lower boiling point than custom made coolant. It probably doesn't do as good a job in dissipating the heat either.
I had this problem on a car years ago - part of the radiator blocked by hard water deposits. Here's how to check for this: Immediately after driving a few miles, open the bon... er, hood, and feel the radiator, taking care not to burn your hand. Check across its full width. If any part of the radiator feels cold, it's blocked. Best solution - new radiator. Not worth buggering about with flushing/chemical treatments if it's that bad.