There are a couple things worth noting here: One, Ainge's account just became verified last week, and it appears he's really starting to enjoy the old twitter machine.
And two, when discussing the greatest shooters ever, you have to think Ainge knows what he's talking about. As a player, Ainge knocked down 1,002 threes over a 14-year career in which he shot .378 from beyond the arc. For eight of those seasons, he also happened to take the floor alongside a guy named Larry Bird. As a GM, Ainge made the 2007 trade to acquire the man who would become the league's all-time three-point leader, Ray Allen.
My credentials in this matter don't quite compare to Ainge's, but I have to say I agree with his assessment of Steph Curry.