He comes at it from a different place than MMT groups, mind. His goal is to run surpluses so that the government may tax less. The goal is to have the government take less money out of the economy over time, which is merely the flipside of adding more in. It's like how people using stimulus cheques to pay off debt liberate money into the economy.
I think he's assuming that employment is nearly full, or within spitting distance of it. Remember that it's politically 'easier' to deficit spend when governments at least have the reputation of running surpluses.
But he's very much not wrong. We don't have enough household savings. Haven't for a long, long time. There's no way to increase wages (or taxes on wages) if the people holding the capital also hold the money and also hold the debt paper. And if the wage-earners are being taxed higher and higher, it's a cycle.
Entitlements were funded differently than the general budget. It was a combination of direct wealth transfer coupled with buying government bonds with the surplus.