I don't think they mark the trails as "open" or "closed." So you may not see a trail sign saying it's closed, but that doesn't necessarily mean it's open. Usually, the trails like Forest Lake, Mineral Basin, Mary Ellen, and the singletrack are all closed 'till at least after the road to the Summit is open.
But I agree, it doesn't sound like the operator at the ranger's district has a clue what's open and what isn't. I'm betting it's pretty sloppy up there still, especially up towards the top of the trails.