>To match and fuel that growth, we hired for a different economic reality than the one we face today.

He kinda did.

That's implying that he never intended these at-will employees to have tenure beyond the short term.

But he didn't. Kind of like how you might get an estimate wrong, it doesn't mean you made an error. Operational decision making are best-guess / heuristic by nature - and he never said he made a mistake in anticipating the economic reality that happened.

What is he taking responsibility for then?

The decision. He was responsible for making it.

If it was the correct decision what responsibility is there to take?

If that was the right decision, none. But it might have been the right decision, it also might not.