PAC is the current Open the Dream Gate Champion for Dragon Gate and didn't want to lose a match while holding the title. For AEW, they are focusing on wins/losses and didn't want to have tie or DQ in the match. AEW is also reportedly looking at things long terms and while they didn't necessarily have a problem with him beating Page, PAC's next opponent was likely Kenny Omega and a win over Omega (or multiple opponents in a row) maybe wasn't in the plans.
The PPV is slotted for four hours, so time was also a consideration as it would take up a big chunk of the show just for a tie/DQ to happen.
Last Saturday, Page showed up at a Wrestle Gate Pro event in Nottingham, England to confront PAC and answer his open challenge. The two had a match where Page won by DQ. Afterwards, PAC took down Page with a chair and told him he wouldn't be coming to Double or Nothing or AEW as a way to write off the match.
So fans could still see a bout between the two wrestlers, AEW released the match today on its YouTube channel, which you can watch above. PAC could still return to the promotion at some point down the road. Page will be on Double or Nothing against a yet to be named opponent.
Double or Nothing will air on B/R Live and traditional PPV for $49.99 at 8 pm ET this Saturday. The Buy In pre-show will stream for free on All Elite Wrestling's YouTube channel. Be sure to join us for complete live coverage of the show.