I'd argue this deal is happening now because the anti trust cases are going in Microsoft's favor. Microsoft and Sony have been in talks for a while to settle the Call of Duty on PlayStation deal but Sony probably thought it would be beneficial to hold off on this deal until the last possible moment in case it gave ammo to the FTC/CMA to stop the merger from happening.
I'd argue this deal is happening now because the anti trust cases are going in Microsoft's favor. Microsoft and Sony have been in talks for a while to settle the Call of Duty on PlayStation deal but Sony probably thought it would be beneficial to hold off on this deal until the last possible moment in case it gave ammo to the FTC/CMA to stop the merger from happening.