The switch is drawing its own power from the neutral while the fixture is being powered from the load, so it’s not the same.
And each device has only one device type handler active on the network. It can’t have two at the same time, it’s just not how zwave works.
That said, you should still be able to get the same end result you want easily – – just wire the current to the bulb so that it bypasses the micro all together and then have the switch toggle the micro, the micro talk to the hub, and the hub talk to the bulb wirelessly. People do this with regular zwave switches, you should also be able to do it with a micro.
In fact, the most common way of doing this is to install a non-loadbearing Z wave switch like the gocontrol auxiliary. It makes the wiring really easy because the switches are not designed to have the load anyway. But it’s the same idea. When you press the switch, the current to the Bulb doesn’t change. Instead, the switch sends a message to the hub and the hub sends a message to the bulb.
These options are covered in the following FAQ: