Reading the study, it looks like they drugged the mice before exposing them to the virus, eliminating the viruses "head start" in infecting the lungs. By the time you test positive, it's probably too late for this drug.
Layman here...
I got the ‘gist’ that an early interferon boost could help with covid and many other viruses... Or maybe just new ones...
You’d have to catch it early, maybe while asymptomatic, or just very soon after symptoms.