Kojima certainly didn't have to, but tweeted, "That title logo is completely fake. Apologies to those who were looking forward to this."
In his tweet, Kojima also added something along the lines that he seemed happy that people still talk about the Metal Gear series. Well, yeah.
Earlier, Kotaku reported that Konami had denied the the "leaked" Metal Gear Solid 5 logo. Kojima's comments should nix any and all lingering doubts.