EI? The only sea routes there are the ones to and from OI, are they not? I can't really see how those would be expected to make a difference. That whole realm could sink into the sea tomorrow along with the accompanying sea routes and very few people would care.
There's definitely an IG justification for creating a sea route or two, and I do think one would be beneficial at this point. I somewhat agree with Chenier's assessment of the situation in the South, though I think there is a possibility for either Fronen or Nothoi to impact a war between Enweil and Riombara.