The senior tennis tour is like three on three basketball - a bunch of old guys trying to do what they used to do. If people want to pay to see something like that, it's their money.
McEnroe is just an old retired tennis player who wants to keep his name out there by trying to create controversy. Who cares what he says? Just pack it up and live out your retirement, John.
Unfortunately, I don't imagine that there's enough interest in a Bill Barron box to make it commercially viable. So that's where old style "hunting and gathering" comes in.