Yellen makes a mistake by opining on things beyond her control ESPECIALLY when it tends to limit her boss's options.

...the idea of a hypothetical asset being marked at $1T but having zero liquidity at that price level...

It would seem that liquidity is irrelevant as long as the Fed would buy it. And, once the crisis has passed, it could be redeemed by the Treasury and melted down or held at Fort Knox for use at a future date if a recalcitrant congress fails to do its job.

Of course, the ideal solution would be for Congress to abolish the law establishing a debt ceiling because, as per the constitution

Fourteenth Amendment, Section 4: The validity of the public debt of the United States, authorized by law, including debts incurred for payment of pensions and bounties for services in suppressing insurrection or rebellion, shall not be questioned.

It is easier to destroy things than to construct them. Republicans, MAGA republicans especially, know that their dreams for America are not wildly popular. They see America becoming a more inclusive society and are feel threatened. As a result, they are willing to tear down American society rather than try to convince people that their ideas have merit. It is like the jealous boyfriend that kills his girlfriend and says: if I can't have her, no one can.