yes, the kids had low risk, but not zero...and, as mentioned already, kids are phenomenal asymptomatic "Spreaders".
These were the early days of the pandemic...many changes were needed to allow schools to open...social distancing...improved ventilation...masking...all the things outlined in Baron's MIT paper that addressed risk reduction in school settings.
I you were a 50+ Grade School teacher in that time, place, environment, I doubt you'd be so sanguine about opening up.
Posts like this just serve to expose what a disaster our "Leader" at that time was...instead of sharing with the American public what he shared with Bob Woodward in Jan. 2020...i.e. COVID-19 was/is a highly contagious and DEADLY virus that requires everyone to do their part in stopping its spread, he did the opposite...no concern for the public...just himself...the Malignant Narcissist, bar none.