As Macedon and Baktria, why Babylon not Seleukeia?

As a Hellen faction having the new center seat of power in Babylon makes no sense when Seleukiea exist. Much less hellenized both in culture and recruitment available.

Why they don't settle in a much more Hellenized Seleukiea instead? To add salt in the wound Helcol lv3 only availble in Seleukiea as well and not Babylon, even more as Makedon which need to demolish the colony before it can built Hellenic admistration since it's upgraded version are only available in Mainland Greek and Anatolia.