This is...it's odd.  It's not exactly a bug, it's not exactly a suggestion, it's just a matter that needs to be corrected sopmewhat so it works right.  If the topic needs moving, then do so.

The Empire AI loves building Sions.  Absolutely loves them.  I can't blame it because Sions are very much monsters if you can pull them out fast enough.  It beelines for the tech, puts down Sion Temples wherever it can, and spams Sions.  LOTS of Sions.  So much so that it goes into debt.  16,000+ into debt.  And it's still spamming them, even though it shouldn't be ABLE to.

It's fairly easy to 'reproduce': Though it's probably bad form to use one bug to watch another, using the mass sight rings to see the map, watch Empires and what they're doing.

I think that for whatever reason, the 'Can you afford this?' checks that happen with other units aren't happening for the Sion.  All that's needed is to make those checks work right so they end up as the elite shock infantry they're kinda meant to be.