They get paid. They are under contract.
Over 65 is considered high-risk, period. Just like being immunocompromised at any age. In those cases right now you also shouldn't be eating at indoor restaurants, doing non-essential errands, or seeing family members without distancing. The reopening does not really apply to you.
Sure, to some extent it's an individual choice, but the team has liability to consider, and if one of them ends up on a ventilator that could end the Twins' whole season.
A little easier to make that call for minor members of the coaching staff though. I don't imagine Dusty Baker and Joe Maddon are taking the year off.