This is true of several respiratory illnesses. For example there's evidence that the flu can increase the chance of a cardiovascular event for several months after recovery[0]. Is there evidence that covid has more severe long term complications than other respiratory illnesses?
>why should we only look at the effects on people younger than 70?
We shouldn't, of course. However we also shouldn't base policy off of a minority of the high risk population. Older people are also at a much higher risk of auto accidents. Instead of making the license process more difficult for everyone, several states have rules specifically for older people mandating more frequent vision tests and license renewals.
Instead of banning a low risk activity for a mostly low risk group, why don't we put resources into taking care of the high risk population(free grocery/medicine delivery, prioritized telehealth appointments, etc.) and let everyone else take care of their own risk assessment?
[0]https://academic.oup.com/eurheartj/article/29/1/96/2398118