I just think McMeniman is the only example of a player 'buggering off overseas' when his state and country needed him. Probably Queensland more than the Wallabies. He left when QLD were still in the doldrums and he was one of their best players every time he stepped on the park (which was rare, I grant you). The Reds struggled to find a lock/blindside of his quality for a while.
I suppose my definition of 'hurt Australian rugby' was not explained well enough. Of course guys like George Smith, Chris Latham, Steve Larkam etc. would have walked into any S14 team at the time of their departure, but they had done years of service and were past their prime. But I was talking more about what Henry was referring to, which was players knicking off before their prime when they had much more to give to their country.