I felt bad but I locked Biscuit up a little early because he really does need to stay off the basement steps. I needed to eat breakfast and get ready to leave. I did visit him for a little bit while I waited for my ride to arrive.
I think I might see if there's a way to put the basement door on temporarily. It needs to be open so the cats can get down to the litter box when Biscuit's in the bathroom but could safely be closed when he's out to keep him from going down there. I don't know what else to do besides keep him locked up all the time. The problem is the door opens out and I don't know if there is enough room where it would be opening for it to be open and for anyone to still be able to move around the house. Plus I'm not sure what to put there to keep it from shutting on its own.