Do you ever think about how Emet-Selch's own rhetoric about the sundered world was the same one that caused the Final Days? The one that caused him to lose everything? He judged the sundered world. The people. Found them unworthy to exist. And eons ago someone else judged his world, his people and found them unworthy to exist.
How dare these malformed creatures exist? How dare they move on? While his own brethren have perished? And isn't what the Endsinger says? How dare the people of our star exist while so many civilizations perished? How dare we hope? To move on?
And that's why him saying "You will not end our journey!" is so important.