The alleged release date of Metal Gear Solid 5: The Phantom Pain was discovered by a certain Mikefancypants, who then put up his “discovery” on the Internet grapevine known as Reddit. Mikefancypants happens to work at a retail store, and claims that the supposed February 24, 2015 date was seen, where the place-holder date used to be December 31, 2014. Apart from that, places such as Microsoft Store, Rakuten, and Smart Game Shopper happen to depict the same date, which could very well be a new place-holder date. Do take into consideration, however, that the 24th of February happens to be a Tuesday, which also is the day where majority of new games are released over in the US.
Basically, until something official is revealed, we will just have to take this particular February 24 date as its release date with a pinch of salt.