Can't Luffy just speedblitz him either way? 🤔
He could, but that depends on the rules of the battle. Moral on/off can decide a lot here. Itachi often uses Gen-Jutsu as first move, even before the battle really starts. This is one of his characteristic features to use Gen-Jutsu against his opponent in the first place. If we change Itachi with Sasuke, then Gen-Jutsu is probably not the first move here. Sasuke didn´t use it often like his brother.
He should be hella faster IIRC
Yes, Luffy should be faster. However, Itachi reacted already to lightning (Kirin) and later to someone who dodged Ay his speed attacks (Naruto). I think Luffy is still a bit faster, he causally kicked lightning away in his fight against Enel and later scaling put him above sub-relativistic to relativistic speed at least in reaction. Luffy should be faster + his precognition allows him another advantage/hard counter here. Also his physics, which are beyond Itachi his own.
course he only does when morals are active usually
Yes. It really depends on that situation and how a character act in the first situation. Since the creator of this matchup never said something about moral, i thought it would be automatically on.