However, playing devils advocate I would argue that 1) not all comorbidities are known. In this study they write: "Very severe comorbidities must have been evident within the six months prior to critical care and documented at or prior to critical care".
This is why I think pathology studies are needed. There are healthy young people who suddenly die while playing football because they have undiagnosed heart problems. Given the relatively low number of young people who die, I am not sure we can exclude this right now.
2) I could not find a breakdown of age for those people who were classified as having severe comorbidities. Even though this number is likely low, I wonder what the overlap is between severe comorbidities and those who died young.
Having said all this. I also believe that current behaviour should be conservative if there is uncertain data. Discussion should be allowed though.
For example, the nursing home workers in Seattle were using CPAP machines on their patients that aerosolized the virus and exposed them all to large amounts of the virus. Theory also applies to subway riders, as outbreaks appear far more severe in areas that rely on public transport with NYC infections following the subway stops with a relatively high correlation.