Yes, the Athenian Colonists is very important and needs to be setup, since you need an Athenian Hoplite. It's worth remembering that in the Persian War, the Athenians gave up Athens and moved the entire population to Salamis (not actually depicted on the map).
Athens had more to lose during the Peloponnesian War, but I wanted to give the Athenians that chance, and that choice. To use the last Muster Hoplite to defend Athens? or place it elsewhere so the Colonists could be used.
Ha ha, wish I'd read this before starting my first solo game. I'm just over halfway through and Athens has already lost its city, and there were no Muster cards left in the draw deck when I tried Emergency Provision! And now they have no cards left in the draw deck at all with 6 turns to go. The end of this game should be interesting!