Quite funny, considering he died a few minutes after that.
Though the OP is wrong about him being Invincible himself you are also wrong about how he died, re-read the manga, Itachi let himself die, any "Invincible" person can do that if they want to.
Itachi didn't let himself die, he just let Sasuke believed that he was the cause of his death when in reality it was his disease that he had finally succumb to.
Juts so you know I don't believe Itachi is Invincible at max just hard to kill, true about his illness but yes he let Sasuke believe he won.