India has a long history of reneging on deals. Once a deal is struck with most nations, that's it. Done deal. With India, they don't care - they'll do whatever is convenient for them.
They did just that on a huge WTO deal years in the making (source: http://www.npr.org/2014/08/10/339292735/why-indias-modi-defi...). The also reneged on a solar energy trade agreement with the U.S (source: http://www.upi.com/Business_News/Energy-Industry/2013/02/07/...).
Hell, even Russia and China won't back out of deals once struck. They'll piss and moan if it turns out they got the short end of the stick, but they'll still honor the deal.
I tell my clients to steer clear of India for this very reason - it's nearly impossible to know when a deal is "solid". There's very little recourse if a business or person reneges on a business deal, or rips you off.
I almost hope facebook wins this little battle; India benefits from facebook pumping a bunch of money into India's infrastructure to build it up, supplying internet to the poor, then India says "Nope, sorry facebook, you gotta go. It was nice having you!". Facebook would get what it deserves. I actually wouldn't be surprised if that happens.