Ramza got it right. Regardless of what actually happened to Squall (did he die or merely faint?), Rinoa woke him up and was able to escape from the weird time-warp they were in using the power of love. As corny as it sounds, this is what Laguna tells us in the Ragnarok before fighting Adel.
I agree.But it only happens in an indirect way.
The direct cause is that Biggs and Wedge were working for Laguna undercover.They just pretend to work for Seifer.
Seifer ordered them to bring our heros back to the future after they defeat Ulti.He also ordered them to activate holographic films on the walls of the Pandora before and after our heros went to Ulti´s time.
The last film was supposed to loop forever in order to kill Squall.
But Laguna ordered them to trick Seifer and stop the film as soon as Rinoa appears.