You can, but biological pops will grow on the planet even if you colonize with Droids. It's kind of weird. I guess depending on ethics you could stop biological growth on the planet and resettle droids in to get to 5 pops. I haven't tried it, but it might work. Droids can't be researchers, so you'd need to do all research on planets you did settle with biological pops until you got Synths which would take a while since you'd likely have bad research until you got them.
At best it would be highly sub-optimal but it could maybe function.
I already deal with this by Colonizing only Tropical Worlds that my Tyraxians are set as Home Planet Type on until I get Droids, THEN use the Droids to Colonize all non-Tropical Worlds with them... till 2.2 anyway...
Immigration causes bio growth on robot colonies, so you can't stop that unless you have immigration controls and zero migration treaties. And the bio-pops don't care about habitability: They will happily move to Space Siberia and then loudly complain about how miserable they are there once they grow.
Which promptly makes me Facepalm & feels like one of the biggest ever modern examples yet of Artificial Stupidity... Even Retards should be capable of reading a Pamphlet describing a advertizing new Colony looking for more Immigration to it, reading the fact that it's a damn TOMB WORLD, then deciding "Hmm... that would suck way too much, to hell with considering this Option."... rather then deciding instead "Hmm... I see no problem with this!" *Packs Bags & goes to Tomb World then feels like they're in living hell then riots at their Government over it even though NO ONE made them go...* -_-
Curiosity: Anyone happen to know whether or not the Devs have ever studied TVTropes? One particular one comes to mind when I see AS powered Pops do these kinds of things...
this one here... & when these people never die when they SHOULD to their own retardation... reminds me of...
this one...
Take the stability hit with population controls and then you don't grow pops on undesirable planets, but your planets that can grow pops get immigration growth from your planets that had population controls enacted.
... Now that I think about it, I forgot that existed... how does it work, benefits vs drawbacks-wise?