Proof that Silva's movement and reflexes is good enough to defend Weidman's takedowns without lowering his hands below his waist.
So Silva dropping his hands wasn't actually a desperate measure to stop takedowns but purely a tactic to taunt his opponents and bait them into over-committing.
With that being said, Weidman had proven to be a striker with comparable reflexes to Silva and that won him the fight. Would love to see a rematch though because it would surely be competitive.