The Island could be contested if Oritilon and Outer Tilog joined forces. They should ally and then confront Lukon in a final war to free the Island and destroy the ring of power. If that fails then Lukon can declare that they won and do their empire thing.
This seems to be the logical course of action. Unfortunately it could not happen for many reasons. As you may have know. OT does accept many refugees from fallen realms, as does Oritolon recently. Unless those refugees rise up to power anytime soon, it is difficult. Maybe those refugees need some helping hand. Thus, the idea of Empire
We'll see how things go though. Oritolon is discussing Valakyrie's proposal now and I couldn't tell you how it will turn out. We might join in. We might tell Lukon where to get off. Or we might just end up in a civil war!
Seems Battlemaster does not have a successful Republic realm
Oritolon realm keeps having rebellions and internal strife all over again.
The old guards seem having a heavy heart to giveup power to the younger generations.
That assumes Oritolon and Outer Tilog would both be willing to fight Lukon in the first place. When first I heard about plans of Lukon's empire I made tentative efforts to oppose them but it quickly became clear that it would have led to civil war in Oritolon (and probably Lukon helping Spearhead back to power). I reached out to Outer Tilog too but they simply shrugged and fair enough I suppose. Their capital is only two regions away from Lukon's. I don't expect they were exactly jumping at the chance to make common cause with mighty Oritolon, who fell apart like an old sack fighting Minas Thalion!
Your assumption about Spearhead is a hit on the head. As long as Spearhead lives, if something happen to Oritolon without his sort-of-agreement, Lukon will march. You surely remember well that Khain our previous Ruler times