I'm going to take a guess as to what the problem night be.....
I think it's easy to misconstrue the sentence....
"The government can never, ever, ever go broke (unless it chooses)."
and misunderstand that sentence to mean;
"The government can spend all it wants, no problem"
MMT'ers realize that the first sentence is, in fact true, but anyone that I know understands MMT realizes that even though a government can pay it's debt, does not mean the the economy couldn't be functionally destroyed. Because a sovereign nation with a fiat currency has debts that are denominated in currency it creates, it can't ever be unable to pay debt, because, as long as government exists, it will be able to create money. The money might be worthless for anything but paying debt, but whether the debt is 1 billion, or 4 quadrillion, these are just numbers and if you can type them into a keyboard then government can pay it.
So when MMT'er say the government will always be able to pay it's debts, is true, but all the MMT'ers I know realize that that does not mean you can spend all you want without consequences.
Amiclose?