No, they should have access to the thureophoroi's and thorakitai's as normal units. The things is, the Successor kingdoms, and Bactria, used greek mercenaries to a great extent to a point that they were an integral part of their armies. There's not a single hellenic army post-Alexander thet did not use a great number of greek mercenaries, including thureophoroi's, thorakitai's, peltasts, etc.