You’re not being unfair….. however neither is a Covid test really in any way a reassurance that he is not infectious. With testing as it is in terms of both reliability of actual tests but also incubation period etc. Testing was never meant to be in order to test individuals as not having it. Testing is not about individuals and verifying they are negative bcause it really can’t do that. Doctors are convinced I had covid back in February and I’m still recovering, but I’ve had 4x negative covid tests and I think i may even have had covid twice, with the second time over 6 months later not being as severe.
The whole point of testing is to monitor and identify the spread of the virus among the population and where possible isolate and quarantine those that are identified as having it in order to reduce overall infection among the population. It was never designed in order to verify safety of those that tested negative nor should it be used for this purpose. It is risk mitigation not risk removal if someone tests negative.
If your ex wants to be an ass that’s his own lookout but if you or and any of your family are vulnerable, ensure you take this into consideraiton with his behaviour and think in terms of an infection control perspective. The first thing the government got right was to say to assume people have it and behave acordingly, that way hopefully the NHS will be able to stay afloat long enough to deploy the vaccine to enough people to be able to manage levels of the disease among the population.
So to summarise no you’re not being unfair, but if anyone vulnerable is in your household or if you are in close contact with anyone vulnerable then a negative test is meaningless.