The answer is no, they would not be prevented from boarding a domestic flight. Canada’s compliance with the TSA no-fly list started in 2011 with the passage of Bill C-42:
Despite section 5 of the Personal Information Protection and Electronic Documents Act, to the extent that that section relates to obligations set out in Schedule 1 to that Act relating to the disclosure of information, and despite subsection 7(3) of that Act, an operator of an aircraft departing from Canada that is due to land in a foreign state or fly over the United States and land outside Canada or of a Canadian aircraft departing from any place outside Canada that is due to land in a foreign state or fly over the United States may, in accordance with the regulations, provide to a competent authority in that foreign state any information that is in the operator’s control relating to persons on board or expected to be on board the aircraft and that is required by the laws of the foreign state.
As we can see, only flights that depart or land outside of Canada are permitted to transmit APIS data to foreign officials and thus domestic flights are exempted. This interpretation is confirmed in the legislative summary published by the Library of Parliament.
Credit:stackoverflow.com‘