It isn’t known whether the addition is a glitch or intentional.
When Konami first announced they were bringing a new patch to Metal Gear Solid 5: The Phantom Pain you probably didn’t think there was going to be a ton of changes. In reality, patch 1.06 brings a rather big change that will allow you to play alongside a buddy that had previously been forced into exile. For those who hate spoilers, you should probably stop reading now.
In the original game play through, players who wanted to actually finish the story, they had to exile the mute sniper Quiet from their Mother Base. Doing so would obviously make her unable to be used as a buddy in any continued play through. It appears this patch has actually given players a work around in order to keep her on the base and use her as a buddy to finish the game.
While it’s not clear whether this was one of the things that was snuck in by Konami on purpose or some werid glitch that will disappear with the next patch, the feature certainly works with the update that just launched. It didn’t take long for Redditors to figure out that if you play through Mission 11 “Cloaked In Silence” where players first met Quiet, seven times she will then return to the Mother Base and will be usable as a buddy through to the end, no matter where you actually are in progress in the game. Metal Gear Solid 5: The Phantom Pain has been known for these kinds of hidden tricks before so it’s possible this was entirely intentional but only time will tell.