Yes, but a major part of your argument is based on things that are not absolutely known. You are telling him to use money to buy a part because it will support more potential customers, however this is possibly false. There might be some people that will only accept 4G for whatever reason, including because this is what has been told to everyone since he decided he wanted to go with 4G. Not everyone that is interested in a Pyra is here, and even some of those that are have stated that 4G might be important for their intended tasks, including playing certain games (which is what the real purpose of the Pyra is).
I still say it is best to try to find a way to make 4G work, and if that can't happen then contact preorder customers and ask them if they would be willing to go with 3G instead.