I do have to point out that MMT does not claim "that a government can... ." It says that inflation is the only indicator of 'too much money', at which point government would be required to run a budget surplus (less spending/increased taxes). [Good luck with that, eh?]
One key to less domestic inflation in the U.S., however it might be measured, has been the importation of the same items made less expensively in China, etc. Those lower prices are now the baseline for the economy. Whether those prices can remain low is, I think, the big question; the answer will depend on the (political) decisions of China's regime.