not sure if he spawns in multiple spots, but the screenshot is the same place I've saw him before, and it's the first floor, at the very North-East room, east of the North stairs.
Top maybe the only spot. I can't remember for sure, if it was the 1st or 3rd floor room there. Names in all 3 floors of that room though, so a good camping area in general :) The posted screenshot still looks liek 1st floor, but my own personal screenshot has him on the 3rd floor.