The authorities have not restricted road travel. The "advice / recommendations / strong urgings" are not a travel ban. The wording is that you "should not" travel, rather than you "shall not" travel. Not traveling is a pretty good idea in many or even most instances, but it is possible to travel without getting close to other people. If you decide to travel to go sledding, you might consider being quiet about it, lest you add to the furor and make things worse for everyone.
The provincial government has said snowmobile trails are allowed to open. The ofsc has stated it's policy will be to deem as "unavailable" trails that connect health units regions with an unequal prevalance of covid. In other words ofsc is doing what it can, to restrict snowmobiling between regions. It is not within ofsc's mandate to control road travel, but they have made road travel "recommendations " consistent with the recommendations of health units and the province.
Participate in road travel if you must, but make darn sure not to contract or spread Covid while doing so. Do not ride on unavailable trails, as per normal.