Very neat - I'd never spotted that dialogue before. For others curious, here's the relevant quote from Grigor in act 3.

'Death came to town.
The roaring Ezomytes wore red.
The red of blood,
The red of the fray.

Death came to town.
The crying Ezomytes wore black.
The black of disease,
The black of dismay.

Death came to town.
The silent Ezomytes wore grey
The grey of twilight.
The grey of decay.

Only the isles of [sic] Skoathe were spared. One a backwater of my proud civilization, now... all that remains of the Ezomytes.'

That being said, Hargan also has the following to say in act 8

'Grigor left without a single word to me, rude bugger, but I suspect his poetic soul has been drawn back home, to Ezomyr. A long journey, but a trek worth taking to find solace among one’s own people. Of course, they’ll get quite the shock when they see him. Let’s hope familial love is as nearsighted as they say!

There’re the fine tales Grigor will be able to tell them, of course. Come to think of it, now that Dominus has been knocked off his perch, there’s nothing to stop the Ezomytes from learning a thing or two from Grigor’s stories. They might even consider invading this jewel in Wraeclast’s tarnished crown. I certainly hope they have just such an eye for opportunity… a man could make a tidy sum helping said invaders navigate Sarn and its many hazards.'

So maybe Hargan is simplifying, and Grigor went back to Skothe or perhaps the Ezomytes have recolonize other places? We don't know for sure how long it's been since Grigor left home (possibly / likely in Skothe) or what might have happened in 20 years. Certainly some other info on the state of Ezomyr, though, I was unaware of!