Also the more 'uninfected' you'll detect. The ratio matters here, not the number.
You and he miss the point entirely. The more testing a region can show is being done, whether negative or positive outcomes, the more 'ready to open' they seem to be. That is why they tout their number of tests as a positive thing. Trump is hurting his own agenda when he says stupid things like that. Less testing means less likely to be able to reopen.