That's not how the Chinese owned debt works. They can't ask for it all at once for one. Second, their currency is directly tied to our economy because of the debt owed. If they tried to ruin the United States over debt, it would crash their currency. China can't and wouldn't have any interest in trying to do something like asking for their debts to be paid back.
That's not how bonds work. Nothing in bond contracts entitles you to "request payment" immediately from the issuer. You can sell your holdings for an upfront payment, and if China did that, it would be fine for us and disastrous for them.
I have to disagree here.