Was the lake itself natural? Or man made? If it is natural then it is crown land and is for everyone's use. But after looking into it a bit more I am not sure if I am right about being able to cross private land to get to a crown lake, even if the lake is surrounded by private land. (See Preston Lake, crown lake, surrounded by private land, several country clubs, closed to public access, and not so pristine anymore) I may not agree with it, as I think a crown owned lake should be for everyones enjoyment, but I would never do what that clown did and try to bully my way across private land to launch into a pristine lake. Chances are that outboard motors were off limits for the lake anyway.
Cheers.