Only if managerial or executive duties are the primary part of both the Canadian year and the proposed U.S. role. Occasional hands-on work does not disqualify him; a role that is mostly production with supervision on the side does.
Primarily managerial means most of the week
The regulation asks whether the position is primarily managerial, which in practice means the greater part of the transferee's time is spent directing people or an essential function, setting goals, and exercising authority over hiring, discipline and resources. Hypothetical example: the South Frontenac manager supervises two shift leads and twelve operators, prepares the production schedule, signs off on aggregate purchases and interviews every new hire, but also runs the batch plant two mornings a week when a lead is off. That role can be described honestly as primarily managerial.
If instead he is the plant's only qualified batch operator and manages in the gaps, the petition should not be filed as L-1A until the U.S. plant has enough staff to change that. Write the duty allocation for both roles in percentages, keep it consistent with the organizational charts, and expect the examiner to ask who does the production work in Pennsylvania if he does not.
An L-1A review should produce an organisation chart tied to payroll and a realistic division of duties for both countries. Hypothetical example: a Canadian commercial bakery promotes its operations director to lead a newly acquired U.S. wholesale facility.
Time sheets, staff rosters, delegated purchasing authority, and hiring records show whether she directs the enterprise or mainly fills baking shifts. The company must decide whether to hire enough operational staff before filing; calling a working supervisor an executive does not alter what the records show. Any qualifying foreign employment must still amount to one uninterrupted year inside the relevant three-year window.