Bronchoalveolar lavage (BAL) is a technique utilized to diagnose lower respiratory tract illnesses. The premise is you basically put a tube in the lung, inject sterile saline and suction it back and now you have a specimen to diagnose infections, including covid19. When he said "inject it, into the lungs it could clean it" he may have been saying they are looking at a way to directly kill the virus in the lungs. While I've never heard of BAL being used therapeutically in this way, I don't pretend to know what the CDC or any government run research has shown. It could be theoretically possible to inject a "disinfectant" (not fucking bleach) but something that kills the virus, into the lungs to sterilize them. The virus is not only present in the lungs however. But, it's an interesting thought. It would have to be something absorbed by the lungs and that either inhibits viral replication or viral entry into the cell. Just some food for thought