He is being grown-up, and he's being a realist. If Congress refuses to curb it's deficit-spending ways, then there is no choice but to increase taxation and try to get more revenues. Current deficit spending levels are unsustainable, so it's either cut back on spending or increase taxation.
Volker said "if we can't do it on the cost side" - if we cannot curb spending - "we've got to go on the revenue side" - increase taxation.
It's quite grown-up, it faces and addresses the problem straight on. If Congress does not curb deficit spending there is no other option but to increase taxation. And since our economy is essentially a consumption-based economy, you have to look at taxation of consumption. Sales tax or VAT, you pick.
You are right - sigh. I just would have liked for Volcker to push the cuts in spending angle more forcefully.