I'll take the PPV piece of this first - AEW's PPVs were previously carried in the US by BleacherReport.com, a Turner/TNT Sports website, but it never made a ton of sense in that B/R never had a TV-centric streaming app, so to have PPVs move to Max is really more lateral than anything else.
As far as live-streaming AEW programming, I have to assume this is viewed as a way to stay competitive with Netflix (which will be taking on WWE Raw in the US and ALL WWE programming - new and archived - internationally starting in 2025) and Peacock (which is still the home of the WWE"s back catalog [save for NXT, which has moved to the CW app] and Premium Live Events). Zaslav would be foolish to think this is somehow going to fill the Shaq-sized hole created by losing rights to the NBA, but rasslin' has proven to be a consistent revenue draw, so there is some logic in maintaining the relationship.