Work apparently wasn't progressing as they liked and the studio was bogged down by the lawsuit with Acti. Seems that was enough to force EA's hand and seek out funding from elsewhere so they weren't completely on the hook should anything happen.
Activision offered a deal worth tens of millions to both Zampella and West, they revised their stance and paid the bonuses to former Infinity Ward devs, they even settled with EA.
They would never do that if they had a strong case.
I fail to see how EA could be so concerned with the trial that they looked for MS for help considering how everything ended. EA offered to cover up the legal costs of the lawsuit from the start, you don't do that without a pretty good idea of what you're getting into. They knew their chances of victory and they didn't care about those costs, they just wanted another 1 billion franchise.
I also doubt MS would get into a fight between the 2 biggest publishers in the industry.
Both parties settled around may 2012, two years before the game launched. There is no way the exclusivity deal was made before that. I doubt there was much of a game by then.
All we have to back up this claim is a MS funded video, saying MS saved the game. That's just too convenient IMO and why I'm skeptic.
I still believe Titanfall didn't need the exclusivity deal, and I think it hurt the IP a bit in the end.
The only exclusivity deal done right in these past months is Sunset Overdrive IMO.