A Crow Cawed

Let's get this sequence straight. Jack Havig joins the Eyrie half way through its two hundred year long Phase One. By that time, the Sachem, Wallis, has:

met himself, very old, at the end of Phase One;

made a single visit to Phase Two;

gone further uptime for glimpses of Phase Three;

written his book, describing all this.

Later, he makes one more visit to the end of Phase One when he is told that he and some of his chief lieutenants will disappear. He himself will never be seen again apart from the single visit that he has already made to Phase Two.

"Faintly, the words pricked Havig's returning apathy.
"'What do you supposed will have happened?' he asked.
"'Why, the thing I wrote about,' Wallis exulted. 'The reward. Our work done, we were called to the far future and made young forever. Like unto gods.'
"In the sky outside, a crow cawed."
-Poul Anderson, There Will Be Time (New York, 1973), XII, p. 137.

Why does Anderson tell us that a crow cawed just at that moment? It can only be to comment on Wallis' hubris. We imagine a crow picking an eye from a corpse, e.g.: here.