The difference with AI-Ptolemaioi is that they won't have their heaviest Hellenistic recruitment pools in Egypt depleted, the way the player would.
For the player, there's something of a dichotomy. Pselkis is in an underdeveloped province on your southern-most border, with little to recommend it at the start. However, it's also the source of half the mining income for the entire faction, so it can't be ignored.