These skills are more about understanding the human mind, which Kalashtar have intimate experience with.
Insight is probably the most apropos, because it is the skill of understanding emotion and human behavior. (not just "detect lies"... I would challenge DM's when giving results to Insight checks to avoid concrete information. Instead say something like "It looks like he's holding something back" or "She's afraid of something, but you don't know what." and let the player figure out what to do with that information.)
Performance isn't just your art, but also how well you can use your art to entertain or amuse. Kalashtar have an edge because of their ability to "read a crowd"
Intimidation is less about how much scarier Kalashtar are than other people, but they have special insight into what scares people.
Persuasion is about figuring out what other people want.
Deception I think would be a good candidate for the list. If I had to justify it's exclusion, I would say it's because studying others can only get you so far when it comes to a well-crafted lie. Often all it does is tell you whether your lie worked or not (which would be Insight) but doesn't necessarily help you craft the lie. Unlike performance, where you usually get an extended period of time to observe others and adjust your performance accordingly, with Deception you get one shot. It's more about selling it and self-confidence than reading other people.
