He did opt out of the shortened covid season.
I believe Greinke had social anxiety disorder?
Pure speculation because I don't know what the situation is with Erod but there is still stigma even today associated with mental health. For a macho professional athlete, that has to be amplified about 1000 more than someone who is not in the spotlight. Whatever the situation is, it seems easier to avoid at this point, even if it is costing a lot of money.