went up yesterday. just got back. No problems in a low clearance 2 wheel drive sedan all the way to the slide where everyone else parked. Lots of people up there. One group of 6-8 hikers tenting it at twin lakes. One group of quadders (one atv one side-by-side) one group of day hikers (to the cabin and back) and one pair of goat hunters.
Unless restrictions have changed since last year, I think ATVers are restricted to stay on existing tracks/roads above 1700m. Motor vehicle closures are in place in the Lillooet area above ~1900m.
The closure above 1900m is not for the entire Lillooet area, but for a few places north of Carpenter lake. The Blowdown road is easily drivable in a 4x4 to the Stein boundary at about 2200 m. Motorized traffic on the way to Twin Lakes is perfectly fine. It's not a park, nor there are any closures specific to it. Hikers simply like to think that as soon as they set their foot on a dirt road (which they call a hiking trail) it now automatically belongs to them, even though other recreational groups have used it for decades.