He does state "As far as I know the screw is not original" so we can't really accuse him of trying to be dishonest. The pedal does look kind of funny though with the giant screw.
My computer has screws like that holding the cover in place. I unscrewed one and tested it on a Boss pedal. The threading is the same so it actually fits but it look redicilous
The switch took place around the same time as the serial number changed from 4 to 6 digits. Most 0500 CE-2s I've seen has silver screw. Most 0xxx00 CE-2s have had black screws. I've seen less than 10 pedals with serial numbers in this range so the statistical material is somewhat thin.