He basically makes the same points I made.
He's not particularly concerned whether it is literally "impossible" to burden future generations like Nick was. He says it's possible - I agree. He's more concerned about whether it's responsible or makes sense to talk about "burdening future generations with debt" the way we talk about personal debt.
It depends a lot on whether we're talking about investing or consuming. Nick's post was all about consumption.
One thing I've pointed out is that when we do straight young-people-let-old-people-consume-more-now stuff with government (at least in the United States), we don't finance it with debt. So I have to wonder how much Nick's "cohort A consumes more apples" model really tells us about public debt (again, in the United States at least). It's very good at telling us that we shouldn't borrow money to give old people Social Security checks - but then, we already knew that, didn't we?