As I said in Post #77, it does not appear possible to "traverse" the facility by bus. Once you enter, you have to exit the bus while still on the facility.
But, even so, asking for and getting IDs from riders on a bus will demonstrate to a guard who is a regular and who is a stranger after about a week.
So will getting on and looking around. It's indicated he wasn't actually looking at the info on the IDs, so let's just drop that pretense.