Does it? Do colonies lose settlers over time if a colony can't grow but is taken at like 60%? I've never actually researched this kind of stuff before.
Yes, if you lower the slider to minimum colonies lose 100 settlers per year or something. You have to fund 50% for them to just break even in yearly growth rate (though the colonist % chance of improving a colony will still function).
I was assuming that a colony not supplied would be a colony not costing money.The cost of such an exploit would be pretty ridiculous though; keep in mind the ducat cost per colony over your number of colonists is exponentially increasing.