Interestingly, an user accepted a credit offer then 12hrs later let the deal expire, thus I have the collateral and they have the token.
A key take away is that if the borrowed amount and the collateral 100% equal, to repay the debt offer before the time limit would incur a fee of 0.2-1 BTS for no benefit, other than their theoretical DEX credit score impact.
By letting it expire there are no fees for the same effect, so it's likely that I'd need to continuously top up my USDT balance within each credit offer as they'll likely let it expire without repayment.