He may be waiting for other offers, but there's a chance he might be able to fit in with Brooklyn.
Going under the assumption that Gibbs is a point guard, he could be an option for the Nets. The team had a whopping 22 players log minutes for them last season, but only had two true point guards (at least according to ESPN's slotting of players by position) - Deron Williams and Jordan Farmar.
Williams is one of the best point guards in the NBA, but he's a free agent and is reportedly down to choosing the Nets or the Dallas Mavericks. The Mavs have, understandably, been coming at him hard, hoping to pair him with Dirk Nowitzki. He could certainly return to Brooklyn, but it's no guarantee at this point. All you need to know is that if Williams returns, the Nets have about 35 minutes less to worry about filling with another guard. But if he doesn't, they'll be looking for help.
Farmar posted a career-high in points last seasonb, scoring more than ten a game. A reliable backup, he's someone that would log more minutes than Gibbs. But he is potentially opting out of his contract and at least willing to see what the open market might hold.
If the Nets lost both of those guys, opportunities would abound. The team is at least a bit prepared with a backup plan, trading for Kansas guard, Tyshawn Taylor, during the draft after the Portland Trailblazers selected him. But if both left, the Nets will probably need to go the free agent route to pick up another player with some more experience.
With so much uncertainty, it's makes sense that Gibbs is taking his time. If both came back to the Nets, his chances to play (or even make the squad) would diminish severely. With Williams, Farmar, and Taylor all on board, it's hard to see Gibbs getting much of a chance.