Forza/MS were the main sponsor of 24 Hrs Le Mans one year, they didn't "lock it up" in their game. There is no need to do so just because you sponsor the real event. It's their choice to sponsor it, nobody is forcing them to cough up.
Eh, when was Forza the "main" sponsor for Le Mans, I'd like to see that article. I've never once heard about that. I know they sponsored a V8 Super Car Team at Bathurst, but the whole Le Man's, never heard of this. I'll do some research. Be back with details.
Wrong, if they are the major sponsor if they pull out then the race may not happen at all.
Edit:
"“Forza Motorsport” was there, not only represented by an amazing driver, but also as an official sponsor for the world’s premiere sports car racing event.
Read more at
http://news.xbox.com/2014/06/19/games-forza-represents-at-le-mans/#3UcTWDAuM5CSomZe.99"
Major sponsor no, official sponsor yes, just like a myriad of other official sponsors like Gran Turismo always is an official sponsor for ALMS and Le Mans. Major Sponsor means you sponsor the event itself in a big way. Gran Turismo isn't a major sponsor for Le Mans but their logos are on every car in the races, hmm might be more to this than I thought. Will do more digging. That quote came straight from MS Xbox page article on Le Mans from a few years back.
Also you are forgetting that these are competing products, I doubt PD pushed for exclusivity at all. They are a Sony owned studio so more than likely Sony pushed for it, PD has no choice but to abide by the management rules stipulated. PD as long as they've been around have never been ones to exclusively lock down anything, they just get things included in the game and go with that. This whole exchange is something wildly different and probably something that Sony themselves are getting into the details and laying out rules. This might be Sony taking control of PD away from Kaz, just like folks have been complaining they should have done. From the complaints in the comments, folks aren't liking what they wished for so much.
Honestly I don't see the point in exclusivity on PPHC, when was the last time that showed up in a top selling racing game? Heck I only hear about PPHC in passing, didn't know until last year that it was paved with asphalt, quite different from the old dirt it used to be ages ago. Sony is just messing up PD's flow with this business minded crap.