What's in it for him?
In part, his legacy as a president at A&M. Gates is a very smart man. Bowen's legacy at A&M is as the worst president in school history, in large part because he guttered Bonfire.
That's on the simplistic side.
On the political side, Bush 41 and Gov. Perry had a lot to do with Gates appointment (as well as certain Board of Regents members), and it was made clear to him that one of his tasks before he left was to bring back Bonfire.
Gates was head of the CIA when 41 was in office, and there's a lot of politics and friendships there.
So why would Gates want to bring it back?
1. Politics
2. Friendships
3. He wouldn't be where he is if it weren't for #1 and #2, which are tied in part to the insistence he return Bonfire to campus
4. Legacy at Texas A&M