There's also harm if you don't tell them a correct result. There's especially harm if you stop testing their neighbors to monitor community spread during a fucking global pandemic over this pointless red tape about providing results.
Thank you for elevating the discourse with phrases like "fucking global pandemic over this pointless red tape". A global pandemic is exactly when we should be thinking hard instead of trading insults.
Pointing out that someone is using silly language with pointless effect is not an "ad hominem attack": can you point out anyone who might be confused by what I said?
Your use of "my friend" is similar to the thing you're complaining about. I got what you mean. Bringing up "ad hominem" is dodging the real issue.
Another comment of yours: "utterly stupid bureaucracy"
I think it’s more nuanced than that (see my other comment).
If you have a false negative, then maybe they spread the disease more than they might have otherwise (unwittingly, but now with the “certainty” they don’t have it).
If you have a false positive, the main downside is from people who think “great, I’ve had it / got it, I’ll be immune shortly”. So that’s the main risk to them.
In addition to the points raised above, a false positive could also have negative impacts on income (unpaid sick leave to self-quarantine).
The false negative hypothesis is facile; even if you don't have it, you can still get it. Ignoring social distancing on that basis wouldn't be any more sensible than doing so without the test. To the extent that some people are just idiots, a false negative diagnosis does not change that.
There is also harm to telling them other incorrect facts, but we generally consider a ministry of truth to be a bad idea. Yet we tolerate the ministry of food and drug truth. This story underlines the cost of that.
I expect the ministry of food science and the ministry of drug science to be scientific. That's quite different from what you're talking about.
I have noticed that your comment is quite typical for people who want to say that we live in a post-truth world. There are certainly problems, but one solution is to double down on science.