Board Thread:Metal Gear Solid V/@comment-180.191.222.139-20140223073630/@comment-50.186.50.212-20140301204005

Revenge for what? One of Gene's primary motives was to see who would be the Boss's true heir (in this sense, you can say he was sparring with Naked Snake). After Snake bested him, he embraced his fate and passed his resources on to him presumably because he had the foresight to know Snake would end up in a position similar to his own in the future.

By Ground Zeroes, we see that Snake has indeed become the de facto leader of a similar hierarchy. If Skullface is Gene, this would completely undermine his dying words and actions in Portable Ops.