From the article:
“Alternative Fiscal Scenario. This forecast is what CBO actually projects future taxes and spending to be given not just the laws in place, but also how Congress and the Administration have been bending and changing the laws through time. In short, the Alternative Fiscal Scenario (AFS) is what the CBO thinks we’re facing absent a truly dramatic and sustained shift in fiscal policy.”
Like I said what a politician promises another can unpromise. These are not “liabilities” they are politcal promises which are more like wishes.
If I borrow money (or my company) from you, or make a promise to you, I am obligated to pay it. I can have assets seized, my check garnished, or even go to jail if I engaged in fraudulent behavior towards you.
None of that applies to our governments. That is why it is called sovereign debt. It is debt issued by the sovereign and and is secured by the sovereign. Should the sovereign decide not pay there is no recourse.
CBO can say what they wish but their projections do not turn promises into liabilities in any normal sense of the word.