It would be technically possible to build up from the LHT frameset using 7-speed components. Or to do the opposite and buy the LHT complete and sell/trade the 9 speed drivetrain / shifters for a 7-speed. If he has a 7-speed bike which has the components he likes, he can switch them over to a LHT and sell what he takes off.
All this of course would take some technical knowledge.