Since this is an ESRB reel, and the point is to show off anything that can affect rating, I think we would have seen snake, since he uses real weapons, like a rocket launcher, mortar, grenades, etc. Sexual content (as seen from boob/butt trophy shots), crude humor (like giant noses, wario wafts, etc), language (devil car, demon king), gambling (spectator mode), and of course, violence which includes real weapons.
As per ESRB:
Cartoon Violence - Violent actions involving cartoon-like situations and characters. May include violence where a character is unharmed after the action has been inflicted
Comic Mischief - Depictions or dialogue involving slapstick or suggestive humor
Crude Humor - Depictions or dialogue involving vulgar antics, including “bathroom” humor
Fantasy Violence - Violent actions of a fantasy nature, involving human or non-human characters in situations easily distinguishable from real life
Intense Violence - Graphic and realistic-looking depictions of physical conflict. May involve extreme and/or realistic blood, gore, weapons and depictions of human injury and death
Language - Mild to moderate use of profanity
Simulated Gambling - Player can gamble without betting or wagering real cash or currency
Strong Language - Explicit and/or frequent use of profanity
Suggestive Themes - Mild provocative references or materials
They have to submit stuff so that ESRB can judge whether or not the content matches their criteria and then give it a proper rating.
Considering they mention this, for likely that same reason:
it means snake will at least not be in the base game. Or that the leak doesn't have EVERYTHING. That said, It's very likely that if he's in at all, he'll be DLC.
