The Nakamura-Kasparov incident during the Ultimate Blitz tournament in St. Louis is getting a lot of confusing attention on other websites.
Are there different touch-move rules for blitz?
You can see what happened on YouTube.
Can Nakamura decline to invoke the rule?
And does anyone understand what Seirwan was saying?
In any FIDE rated competition in which the arbiter observes that act and does his or her job, the move is Nb4, level of supervision notwithstanding. FLC 4.7.
However, the right of a player to make a claim against an opponent who has violated FLC 4.1 through 4.7 is forfeited when the player touches a piece with the intention of moving it. FLC 4.8.
The arbiter either did not observe or failed to appropriately act when observing Kasparov playing Nb4; otherwise, Kasparov would have been directed to play Nb4. Faced with this situation, it was incumbent on Naka to make a claim before touching the piece. When Naka touched the knight to play Nxf4, his right to claim ended.
Of course, this may not have been FIDE rated, in which case all bets are off. Under the abomination that is clock move, Kasparov’s conduct is perfectly legal. Maybe that’s what the sponsors wanted.