Spartan Colony in Libya

I was reading about Leonidas on Wikipedia when I came across his brother Dorieus, and how he became unsatisfied after his half brother Cleomenes became king instead of himself. Then he went on to attempt and colonize Libya! But the Carthaginians kicked them out, and Dorieus died when attempting to colonize Sicily. But what if he had succeeded? The POD I have in mind is the Carthaginians being weaker/having domestic problems so the Spartans can establish a colony in Libya, and giving them the possibility of incorporating the entire empire into the Spartan colony if the Carthaginians topple! Is this even plausible? Glad to hear anyone's thought on this!
 
Maybe they let him colonize because they want to get more people living there? Then when the carthaginians are busy, his little colony gains power and replaces them?
 
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