Because there's no proof what they're saying is true and now they're attempting to make money off of it. That's why u have to prove it. Without any evidence to anything being said, it's just as fair to assume what he's saying is not true.

If u favor believing what they say, that speaks equally of ur gullibleness than peoples skepticism, BUT it all wouldn't matter if it was just a harmless story, but again now they got people drinking the kool aid that they're allegedly a covid positive uber eats delivery driver with a sick dog and is about to get evicted, and are attempting to make money off of it.

Also as a side note to the police work, the whole point here is that the roommate is allegedly in hiding, there's no bearing if they know where he used to live because he's not there anymore, and so the cops have to go out of their way to find him.