If you've been an electronics engineer long enough to be able to design this radio, you almost certainly know the resistors are needed, or can discover it with

If you've been an electronics engineer long enough to be able to design this radio, you almost certainly know the resistors are needed, or can discover it with a single Google search ("PCB design micro USB to C upgrade"). A more likely story is cost savings. It's cheaper not to support it, from an assembly and testing point of view.