She may accompany you in TD status, but TD does not authorize employment, and freelance work performed in the United States is employment. She would need her own basis, such as a TN application in her own right if she qualifies.
Freelance is still work
Hypothetical example: the spouse of a Rothesay TN accountant does bookkeeping for a handful of Canadian small businesses and plans to continue for them from the couple's U.S. apartment. TD status permits her presence and permits study, but not employment, and the location where the work is physically performed is what matters, not the location of the clients or the currency of payment.
If she holds a Canadian accounting designation or a relevant degree, and a U.S. employer or her Canadian employer arranges a defined professional engagement, she could seek TN as an accountant in her own right. The arrangement must not amount to U.S.
self-employment, and any ownership in the entity receiving her services must be disclosed and assessed rather than treated as an automatic bar. If she does not qualify, her options in TD status are to study or to pause the practice. The household should decide this before she gives her clients any commitment.