The fact that he didn't tell the gov't of Canada that he is going to be talking to White House officials is pretty scummy. You would never accept that sort of behaviour from another former PM if it was Conservatives in power. Hopefully it hurt Conservatives at the polls. Sending shadow diplomats to undermine Canada's position probably won't play well.
Pardon me, but is there some requirement that former politicians keep the Canadian government briefed on who they're going to see and what they're going to talk about?
Harper does not represent the Canadian government, and makes no pretense otherwise. Nor do the Americans think he does. So eh can hardly be undermining the Canadian government's position. Nor is he likely to want to given he has expressed support for the Canadian government's trade positions recently.