It's not quite the same ethically: for all of this to work you should make this attenuated virus spread faster than the more deadly ones, so there is a positive

It's not quite the same ethically: for all of this to work you should make this attenuated virus spread faster than the more deadly ones, so there is a positive act to be made which goes directly against the Hippocratic oath (do no harm). Immunodepressed subjects right now are protected by isolation and by the fact that right now a smallish percentage of the general population is an asymptomatic carrier, if we were to start spreading this actively those variables would change.