Michael
Although it does not seem to say so I assume it applies to handicapped persons. The exit stairs on the downside are not antway suitable for wheelchairs , not is the bridge. They would be quite entitled at all times for taxi from good old Sydenham. This would be great revenue for taxi drivers.
I agree Michael if station is unmanned both sides then no reason for locking the gate to the stairs.
But please some of the suggestions would be intimidating for the staff.