Via the IGN video (5:50).
Kojima:
I guess the less Kiefer the better. ¯\_(ツ
_/¯
Kojima:
"As much as possible, Snake will act based on the player rather than doing things like making spontaneous comments or flirting with women. In fact. this time, Snake won't really speak much at all. MGS5 is an open world game focused on giving freedom to the player who will drive Snake's action. Snake himself will be more of a silent protagonist similar to Mad Max in Mad Max 2. It's the characters around him who will expand the story."
I guess the less Kiefer the better. ¯\_(ツ