In theory the two are about fifteen years apart for game-internal date.
The conceptual problem is that the Zhodani "stopped expanding" a thousand years ago.
If the new zone was annexed in response to some external concerns the Consulate might make an exception, but that also happens to be the sector row the Empress Wave was plowing through during the Classic and early Rebellion era (not that DGP would have known that). The Zhodani were ill-equipped to go claiming new territory in that neighborhood, unless they decided to hop over the Wave and "rescue" (study, conquer, etc) those free worlds scrambled by it.
As an unrelated note, that sector has some UWP issues. Repeated worlds, and an interesting interpretation of the MGT model for Zhodani worlds. Instead of stripping worlds that rolled a Pop 3 or less down to Barren, all such worlds were apparently promoted to Pop 4.