I'm sort of wondering what logic they are using in the hard code. If I was implementing this, I would use something along the lines of "if target_grav_sbcount >= player_max_sb_count then deny" or "if target_grav_sbcount > 1 then deny". Right now, it seems more of a "if target_grav_maxsbcount > 1 then deny" logic.
Cursix
By itself; I construct a single starbase and try to move it to an adjacent world that has no starbases. The game denies the move claiming I already have a starbase in that gravity well.
In this case, my mod grants the research modifier. The issue is however when you build a Vasari rebel SB and try to move it to another gravity well, regardless if it has a SB (or ever had one for that matter), the game believes there is already a starbase and rejects the order.
Rats... Thanks for letting me know.
I've created an artifact that increases the max number of starbases by 1, similar to how the "Twin Base" ability grants Tec Loyalists an additional starbase. However, this seems to break the Vasari Rebel's ability to phase jump their starbases. Regardless if the adjacent destination has any starbases or not, attempting to jump is blocked with the error "Cannot enter hyperspace because you already have a Starbase at that gravity well." I've looked around and so far have not