Ok but one problem you get across when considering Itachi'd go for Sasuke's rescue if Konoha couldn't do it somehow is /Akatsuki/. What about Kisame? His schedule(did he have a schedule i think so)? Aaand, when Sasuke went to Orochimaru's place, did Itachi get to know it was by choice (because there was a rescue team after him, it might give one some other impression) and how did he get that information?
Itachi is in Akatsuki, yes, but Itachi also has ridiculous amounts of free time. I mean, RIDICULOUS amounts of free time. They’re always paired off traveling and the only semi-important things they do inbetween Jinchuuriki hunting are mercenary missions. Should Itachi feel like traveling to a specific country that has his little brother, he most certainly can. Unless Akatsuki at the moment has another mission for them, Kisame will gladly come along. He will assume Itachi is rescuing Sasuke so he dies at a later date.
As for Sasuke and Orochimaru, this one is mostly fueled by headcanons-- but it’s not entirely without canon basis. Jiraiya mentions he has an Akatsuki informant to Kakashi once, in canon, but...we never know who this is, really. Many (including myself) theorize that this is Itachi himself, given he is literally a double-spy, but though Jiraiya having a spy and Itachi BEING a spy are both things confirmed within canon material, Itachi specifically being Jiraiya’s spy is never something that’s confirmed, though heavily theorized.
By this line of information he could discover that Sasuke abandoned his village, cementing that it was his choice, and not that of a kidnapping.
(And if that doesn’t work, he has crows fucking everywhere.) ]]