Sorry, I missed it. Seems like the source is one that could have an agenda (though not necessarily), but it almost reads similarly to, say, if BP published findings that climate change isn’t occurring.
That said, yes, going to the gym vs. working out at home can be very beneficial to some people. But I would put gyms on the list of places where a vaccine passport would be acceptable to me. Then no one is saying people who want to go to the gym can’t go, they just need to get the vaccine first. It’s not hard.