From a way back...
Colonies requiring admins to exist at all is actually a p. neat way of resolving some of thier issues.
I kinda want this to happen because it also implies you could get rid of the hard cap for colony numbers entirely, as admins then become the limiting factor for them. The player is 'capped' by thier own finances and admin availability there.
That way, there's a soft limit on colony numbers which slowly grows as the player progresses. And they always have the option to (eventually) scatter admins about like alpha cores, so long as they are prepared to handle thier ever growing upkeep.
And it also solves the issue of the player not being guaranteed to have enough colonies to access all resources at meaningful levels and perform additional tech mining.
If you wanted another soft cap you could also raise the upkeep costs of all admins by multiplying it by something like Math.max(0, SQRT(n-3)) to give the player 4 admins at base cost, and every one they add after that increases the cost of all of them.
(I'm bad at Java, apologies if I made a huge hash of that expression.)