Then he should not have signed the article as Director of McGill's Institute for the Study of Canada. If he had not done so he wold not have had to resign. He could have just signed the piece as Andrew Potter, Professor of . . . . .or just Andrew Potter.  If you are going to write a piece as a representative of an academic institution you better know what you are writing about or you risk discrediting the institution, which is what he did. Any first year university student could have written a more credible piece than that!