The dunk here is not on MMT, it's that the head of Biden's council of economic advisors opposes MMT but can't even try to muster a reason why. The woman interviewing him in the video is Stephanie Kelton, author of the Deficit Myth and the main proponent of MMT. She describes (as shouldn't be shocking based on the name of her book) that deficit spending is actually a necessary good to keep the economy functioning, and in that way fits within the left as a counterpoint to criticism of progressive policies like universal healthcare or free college or reparations etc. as "unaffordable."

But your instinct is right, MMT isn't necessarily collaborative with leftist ideas since it isn't concerned with class or redistributive policies. It's basically just a way to explain why we can print so much money and see barely any inflation despite classical economics constantly warning about that exact scenario.