If anyone in the front office or his teammates weren't perfectly okay with his decision, do you honestly think they would say so publicly given how anyone questioning the cost/benefit of ANY Covid-related restrictions on society, the workplace, public places, etc. was universally demonized by 99% of the press? Particularly in spring/early summer of 2020 when not quite enough time had passed to prove many of those policies ineffective/pointless at best??
I'm not going to villify or praise Cain for making the decision he did to opt out during that Covid-shortened season, no matter what his reasoning may have been - to each their own, I will give Cain a hard time if he is trying to argue that his decision to opt out in 2020 was the start of the front office not respecting him enough as a "team leader". To me it seems like he's looking for a way to pile on to the current negative sentiment towards the front office for making the Hader trade, without looking at onfield production and contract status of himself and the other veteran players he hints at being disrespected (Hader included tbh) as the primary reason these personnel decisions were made.
Players reaching free agency love saying, "It's a business" when they are about to play wherever they get the biggest contract from. Well, how Cain's career ended is also part of the same business - and he should be perfectly okay with that side of it, too.