The hook to this whole issue is one of enforcement.
It’s legal to cross the border but once you are in the country, it’s almost impossible to enforce the ‘no driving’ restrictions.
The CBSA don’t even ask or seemingly care what the odometer reads on the way in since they won’t have the opportunity to check it on the way out. Ditto the 6 months rule, you don’t see Canadian authorities on the way out so they don’t know when it crossed back out. Even if you do have interactions with local or Provincial LEO’s they don’t care where it’s registered as long as the license and insurance is current.
The bottom line, it’s a totally toothless regulation that in practice means nothing if people don’t feel like complying with it. Much like CSA Z240 certification. LOL.
