Well, he just says a negative antigen test says very little. A positive can always be useful to isolate someone, but a negative could be positive the day after or before. Besides, omicron is so widespread that there aren't test for everyone. So it's not very reasonable for someone to test every few hours. Many cases are asymptomatic, and if an asymptomatic contact gets tested that could give a positive and help contain spread, but it's already out of control. If somene has symptoms, that's maybe more informatio that a puntual test. I'm no doctor, but if you have an appointment just go and you'll have one data point more.