Have you asked him why? It does sound unneccessary. Do you have any documentation for the router; it may only support 4 devices and it's getting confused.
At work we have wireless but when my laptop is in it's docking station and therefore connected to the wired network that seems to take precedence. It's quicker anyway. Not sure about home; I'll give it a go tonight with both the work lappy and our own, and see what happens