If you've had a test you clearly suspect you have the virus. Therefore you need to go home and isolate until the result. I'm sure the usual ones will shout, but I would see this worthy of a very hefty penalty if you are found not to have done.
Perhaps the authorities should do some checking on this - would be quite easy, as they have the details from the test bookings.
No, I agree with you. That sort of a restriction should be a slam dunk - an easy way to reduce cases that will only inconvenience a tiny minority. I'd gladly support that if it reduces the risk of ever wider shutdowns.