Harky gives a fairly thorough accounting of his feelings on this matter, though there are shades and subtleties to what he’s saying that might be skipped on first reading. He’s not as radical as Hammerhead: he knows that working with the Peacemakers to bring down the Corruptor Beast was the right thing to do for their combined people. Without that decision, a whole settlement would’ve been destroyed, if not all Arkerra.

But his word choice shows the difficulties of his position: “I cannot allow you to do it again.” Harky considers it unlikely that working with humans will be the necessary, only choice in the future, as it was here. But if it were, he knows Penk would do what was necessary. And yet he must punish this and forbid it. His whole political career is basically tied to the platform of “no mercy for the humans.” He can’t recant it without stepping down, and his stepping down just now would be disastrous for the cause, considering his likely replacements as Rebel commanders are Don Gobligno and Iver. (Arfa would put up a fight, but her age and some races’ sexism would probably doom her bid.)

Harky turns back to face the sun, much as he did when he first appointed Penk his herald. Then as now, he sought perspective on the present and visions of the future.