I don't think indeed that the HABmin UI should contain references to Z-Wave either. But since 420 is not merged or completed in any way, I don't think the configuration interface should be part of the binding. It would be there for the sole purpose of running HABmin (or another management interface) and it would be the only binding that has it. 
My idea would be to create a separate bundle for the configuration interface to the Z-Wave binding for now. This way the binding will not end up with a part that needs major refactoring in the future and this way we can have this evolve a bit without it becoming part of the Z-Wave binding itself right now.