No doubt you've seen this story floating around. The reporting on it seems pretty bad to me, and the authors likewise aren't really communicating the disclaimers and context well either when interviewed.
It is very much worst case modeling. They used superspreading events to bound their infectiousness estimates and assumed well-mixed air. So it is more intrinsically viewed as modeling how risky an indoor environment would be if every indoor environment had the worst superspreading conditions. But real-world contact tracing data shows generally most encounters aren't nearly that risky. Long range transmission is certainly possible, but it isn't the norm. Likewise, their time exposure estimates err on the conservative side of low risk tolerance.
I'm not sure I disagree with most of their basic conclusions though on how to avoid infection. Mask wearing by all individuals is extremely important. Indoor time should be limited as much as possible. Ventilation and room volume are extremely important. The risk of indoor transmission goes up as occupancy goes up due to more potentially infectious people, closer contact, and more infectious aerosols. The risk goes up with more strenuous physical activity and yelling/talking/singing. And the typical six foot distancing rule is not necessarily a total panacea indoors, and not as important as time spent in the room and the conditions of the room.
But I think I disagree with how it has been framed. You don't necessarily need to panic about grocery shopping. Distancing does help versus no distancing even indoors. Occupancy limits do help limit risk of infection. And generally long range transmission is much less common than close range transmission, especially if exposure time is low.