Not in TD status, which permits accompanying family members to live in the United States and to study but confers no employment authorization at all. He would need his own basis, whether a listed profession of his own with an American employer, or another category that fits his circumstances.
Give the second adult his own timetable
Start with his citizenship, since a Canadian citizen may be eligible for a professional classification in his own right if his occupation appears in the list and he meets its qualification rule with a prearranged American job. If his trade is regulated, add the state licensing schedule to the calendar as well, because it will be as binding for him as for her. If no route exists for him at present, decide deliberately what he will do: study in dependent status, remain in Ontario for a period, or wait while she establishes herself. What should not happen is a household budget built on income he is not permitted to earn, or casual work taken on the assumption that a small amount is different in kind from a job.
Hypothetical example: a Tyendinaga occupational therapist accepts a U.S. hospital offer while her partner expects to continue a remote Canadian bookkeeping business from their new home. Dependant status does not grant permission to work, even if customers and payroll remain outside the country. Review the partner's activity before the move, choose a separate immigration basis if one exists, and budget for a period without that income if it does not. That choice should be recorded before either adult starts paid activity, not explained later as an accidental experiment.