If you choose not to pay back a 401(k) loan, it converts to an early withdrawal, subject to income taxes at your bracket and a 10% early withdrawal penalty. If you leave your current employer, most plans convert the loan to an early withdrawal.
Heidi's plan was not a 401(k), but another tax-deferred retirement savings plan. The amount she borrowed was above the 401(k) limits. Probably similar rules though.
Bottom line: they borrowed their money from their tax-deferred personal account. Who does that make them slave to, exactly?
Well, I was thinking about the Goldman Sacks loan for the campaign.