Just because Messana was controlled by the Mamertines doesn't mean that delegations couldn't (and didn't) go to both the Carthaginians and Romans seeking intervention on their behalf.

And to better reflect the Mamertine presence, should more of the soldiers in Messana be merc troops? I think there's only a unit of hippeis and iphikrates hoplitai at the moment, in addition to the pantodapoi, akontistai, and militia hoplitai.