This response misses the point.

Yes, it is possible for young healthy people to have complications from COVID.

The thinking must go one step further: what is the likelihood of a deleterious outcome? Is it more than the likelihood than them getting in a crash while on the way to the gym (which we do not prohibit)?

A further question: is the mitigating response impacting other outcomes that are important?

In multi-objective analysis you must consider more than just one factor to arrive at an optimal state. I fear the analysis done by many laymen in this area only considers one factor (COVID infection), and even then, considers it without nuance.