Heat disburses from the freezer through the metal skin, which is why many people build a facade instead of gluing the skin right on... the airgap allows enough movement so that the freezer isn't overworked, thus burning out faster. When I add new kegs, the sides can get hot for a while while the coils radiate heat.
In my opinion, any r value is too much r value, as the mechanism that the design relies on is altered. It may work fine for some, but I imagine long term it just isn't a good idea. If you really want a skin, and dont want to build a facade like in the link you quoted, I would glue furring strips to the sides, and then glue the laminate to that to allow for some air movement.