When you think about it, this would be the perfect place to show Snake returning to Smash Bros. Metal Gear appeals heavily to the Spike audience as well as Smash Bros. What better way to reveal him then by showing him at an event like this. Then for the Monday update to the website, Snake's profile will be added.
Since it's looking like Sakurai wants to reveal most of the Veterans early this time, and we already got Sonic revealed, if Snake is returning then this would be the best place to reveal him.