The position must involve prearranged professional work in an occupation on the USMCA professional list, and the applicant must meet that profession's stated qualification requirement along with the citizenship condition. A Canadian address and an impressive title are not, by themselves, evidence of either.
Compare the duty list against the listed profession's own terms
Set the actual duty description next to the specific wording used for the profession on the list, and identify which document proves the applicant meets the stated qualification. If the employer later changes the role's responsibilities, reassess against the revised duties rather than the original offer. It is possible for an initial review to conclude that the position does not currently match any listed profession; the honest response is to say so, not to redraft the letter until it sounds like a match.