Its not the percent of treasuries they own, its the message it sends. Because of dollar debasement other countries, e.g. Japan are ironically happy to buy US treasuries in an effort to competitively weaken their own currency, its a race to the bottom in an effort to boost exports and grow their own economy.
Yeah? And where do you think all those "domestic and foreign investors" are getting the cash from? Oh yeah... the Fed discount window. Borrow at 0%, buy treasuries, pocket the margin. It's an ongoing undercover bailout of the banksters.