Why didn't the minibus driver take the freeranging taxiway route, surely that would take a lot less time. Presumably he didn't have the appropriate airside driving pass?
I think the only people who have those sort of rights are tug drivers, Airfield Ops, Fire, Police etc.
I wouldn't have thought a minibus driver would get one of those. I doubt you are even allowed a passenger carrying vehicle such as a minibus on the Taxiways anyway unless under escort from Airfield Ops.