I feel like you could have a transfer, they'd just have to spend a year or two at SFA and then some postings on ships before they'd be eligible for the EC panel. Hence that exactly being Xuggaed's background. I imagine there's a few Orizzas -- or minor Apiata queens, for that matter -- who are going to take their chances for climbing the ladder in Starfleet rather than in the Hive. No one's written about them yet is all.
We probably have a few high-ranking Seyek, Fiiral, Qloathi, Caledonians, Indorians, Gaeni, and Orions due to the long times we've had affiliate and affiliate+ status with them, and the subsequent crew flow. Again, they just haven't been written about with maybe the exception of Holena and Dr. Asurva for the Orions.
Actually now that I think about it the lack of senior Starfleet Apiata in any fics despite their popularity is kinda weird.