In reply to skog:you’re right, when I was there last summer, it was open and could be stayed in. The asbestos risk is minimal for one night really.
I’m not sure if this is for health and safety or they genuinely don’t want it used, The estate are very good re access and bothers so I’d hesitate to abuse their good will and stay there on a planned basis. There are great campsites near and beyond the bothy anyway and if you’re cycling in the a small tent is what I would recommend.