FWIW, the MVUM for both the Rio Grande and Carson NF show all of the roads in the area as open. The “closed” road looks like it goes into BLM land, but the Antonito BLM surface map doesn’t depict anything but the northernmost 1/3 of the curve above whiplash, so hard to say.
I’ll be back Friday, and I’ll check the carsonite marker where it breaks off at the top of the hill to see if I can see a trail/road/route number. There are actually TWO routes into the bighorn section house from east/above bighorn eye. One at the bottom of the steep hill, and another at the top of it. The lower road is significantly more challenging, and might be “closed”. The top one is marked on the carsonite as definitely open to motorcycles, and weathered where the sticker for passenger vehicles would be—but as it’s clearly a two track I believe it’s open and on the MVUM.
Dan