There is no judgement on aTriz or other meriters, I think. But he and the other meriters have to be informed. It is also important for aTriz as campaign manager and the forum, to be informed about plagarizm.
To your main point. Single cases like your researched one are not representing the "truth about the Merit system". Only if you would find a majority of Merits/relevant numbers of Merits, given for plagarized posts, would confirm your conclusion.
But it shows, that managers, meriters and we all must pay higher attention to this problem.