Missed opportunity to term out US debt? Easier said than done/Ueda tries to calm JGB market/Maersk and Block

Yes, the US Treasury should have sold many billions/trillions more in longer term debt in 2020 and 2021 than they did relative to short term debt as Stan Druckenmiller used to rightly criticize Janet Yellen as more could have been done. That said however, it's not as clean a story as it seems however logical it sounds. Let's back up first. Steve Mnuchin was Treasury Secretary for a chunk of time when the 10 yr yield was below 2% from July 2019 until he left in January 2021 and he seemed committed to taking advantage of low rates to term out debt but didn't much, outside of reintroducing the 20 yr bond again which was at least something. 

Back in 2016, just a few weeks after the election and Mnuchin was appointed, in an interview on CNBC he said "I think interest rates are going to stay relatively low for the next couple of years...We'll look at potentially extending the maturity of the debt because eventually we are going to have higher interest rates and that is something this country is going to need to deal with." Of course, now is that time. https://www.cnbc.com/2016/11/30/cnbc-transcript-steven-mnuchin-and-wilbur-ross-speak-with-cnbcs-squawk-box-today.html.

In August 2019, Mnuchin told Bloomberg News, "If the conditions are right, then I would anticipate we'll take advantage of long term borrowing and execute on that." In May 2020, Mnuchin was on CNBC and they headlined an online story after an appearance of his, "Mnuchin says he's comfortable spending $3 trillion because Treasury can lock in very low rates." He said in the interview, "We're going to take advantage of refinancing all of our debt..."Between 10 years, 20 years, and 30 years, we're borrowing an awful lot of money long term so that we can lock in this $3 trillion for a very, very long period of time." https://www.cnbc.com/2020/05/11/mnuchin-says-hes-comfortable-spending-3-trillion-because-treasury-can-lock-in-very-low-rates.html

About 6 months later, according to Reuters, "US Treasury studying ultra long bonds, demand queried." https://www.reuters.com/article/us-usa-debt-refunding/u-s-treasury-studying-ultra-long-bonds-demand-queried-idUSKBN17Z1CV.