Having negative trust rating on your account is not an excuse for failing to repay your debt, nor is it the lender's fault that your account received this negative trust rating. Repaying the money you borrowed is your obligation! You shouldn't rely solely on bitcointalk to earn money for repayment; if you're genuinely committed to settling your debt, you'll find a way to do so. Using the excuse that you can't join a signature campaign because of your negative trust rating to avoid paying your debt is simply wrong.