As Canadians we had already decided, coming out of the 1995 referendum, that 50% plus one was something that we didn't endorse in some contexts, so we can't have our cake and eat it too, right?
This is the thing: the thresholds required for referenda are going to be political and are going to be structured by the context in each particular one. The generalities I can draw from the Canadian political process are that in 1995, under a very particular question, there were people in the Canadian federation who said that 50% plus one was simply inadequate. Then the flip side is that 58% was also seen to be simply inadequate as well.
My only point is that having a proper and complete discussion about where we want to draw the line is something that I would advise in the context of referenda in general.