Its been a couple years since I've been up there, so I couldn't comment on whether there are gates up there, but the trail is no where near a 6 (I assume you are talking about the 4 wheelers companion rating). I'd say a 3 tops - a few steepish sections, a bit off camber, but really nothing a stocker would have any difficulty doing. It feels quite remote there so maybe that had some effect on the rating.
Very beautiful spot, but a bit inhospitable for camping - cold and windy even in August - I think the elevation is about 7,500 ft. Alpine meadows, big sweeping valley, etc. Also, no fish. Scenery is worth the trip and there is a nice clearing about 4km back down the trail to camp at.
Hope that helps and that there are no gates on the route.
Dave.