I don't think they'd need one. Drop tower type rides are that simple, that even young children could ride. This being a scare maze, and with their being an age restriction of 15 yrs and over, literally everyone will be of a height where they could easily ride.
No, they would definitely need to advertise it.
Having done the Blackpool Tower Dungeon this morning, it is quite clearly mentioned at the beginning of the attraction that anyone wishing to experience Drop Dead must be a minimum of 1.4m tall, and this is also checked again before the ride section of the attraction begins.
If the drop-tower section of Nemesis: Sub-Terra is to be used in Project 42, a height restriction will need to be advertised and enforced.