A standard seat that adjusts does need to be capable of being moved. That is all. The book doesn't say to 2 or 3 or 23 positions. Just does it move back and forward. Whether that is manually or if electrically then by the electrical switch.
A fixed seat ie a bucket seat is acceptable and therefore doesn't need to move.
Do watch though from the end of this month the term of modified car is being defined in the manual. A rally/track day car with all sorts of mods will be fine. But just changing the steering wheel from airbag to none airbag will not be enough.
