Legality of swapping identical pieces In an offhand blitz game without touch-move, my opponent, on his opening move as White, just to be a wise guy, picked up his b1 knight and put it down on f3, then moved his g1 knight to b1, and punched the clock. He did it all with one hand. Apart from rules against distracting or annoying ones opponent, did he make a legal move?
In an offhand blitz game without touch-move

In other words, you are not playing by the official rules of any chess federation, either national or international. You are playing by your own rules. So, you and your opponent, as the arbiters of the rules you are playing by, are the ones to decide whether or not what was done was legal.