That’s the whole point of quarantine.
It’ not just for the infected, it’s for those who MAY be infected too.
And the dad should be legally liable for the costs of cleaning the venue and anywhere else he shouldn’t have been.
Also the medical expenses of anyone who may get sick as a result of his behavior.
I’m always distinguishing between “people doing the wrong things”, and “chance of actual danger from the wrong things”.
This is an unfortunate learning opportunity.
If nobody at the school tests positive, and nobody gets the virus, what does it tell us?
It tells us that to people in the same house as a known infected person, who then went to a public event, did NOT spread the virus; maybe the virus doesn’t spread as easily as some people think it does.
If a dozen people get it, it tells us the opposite.