Rodan
You appear to be saying that if you see an unverified (e.g. no radio) 7000 return without Mode C, flying "across" an airway whose base is say FL55 and which has traffic in it at say FL65, you have to reroute that airway traffic??
There are many such situations!
I think a lot of people knowingly don't switch Mode C on. In my PPL training it was never switched on. Bizzare...