I don’t know why this is a surprise. Foreign governments have allowed the US to finance its way to an elevated standard of living via a huge trade imbalance. They also soak up a truly staggering amount of public debt, again allowing us to avoid hard choices.
This debt is dollar denominated so what are these soverign wealth funds supposed to do with their greenbacks? Stack them in a safe and let them mold? Nope, if you’ve got a glut of dollars, you might as well purchase US assets that can give some kind of return.
Of course, I wouldn’t put my money into Shitty-bank, Blackstone or the half-assed financial middlemen of Wall Street. But if the Saudis and Chinese feel like doing so, it will wind up about as well as the Japanese did with their big RE purchases in the late 80’s.