Yes if they are travelling and not trying to reset the clock on their stay on the supervisa they should be fine taking a trip to the US and returning to Canada. They will need proof that they have valid supervisa insurance and they apply every year for a new supervisa policy so they always have a valid 1 year supervisa insurance policy. Some have tried to extend their stay on a supervisa by going to the US and trying to reenter Canada. Some get denied entry. If someone want to try to extend their stay on a supervisa they should always apply online. If they have children in the US and Canada and alternate between visiting both countries that can also lead to issues. If they are never returning to their home country it will be clear that they are trying to live between Canada and the US. As visitors they are still supposed to have a home and ties to their home country. It is impossible to say what will happen or how long it will take for either Canadian or US border agents to say something or limit reentry time or entry in general.
