Loan repayment to avoid legal action in home country

My friend left the UAE for family emergency reasons and had a loan debt remaining to the bank.

He continued to pay the instalments for the next 3-4 months but could no longer because he did not have full-time employment. He kept in contact with the bank and let them know his situation.

He only has part-time work while looking for full time and offered to make small payments to show good faith until he is able to secure full-time work.

Now the loan is with a collection agency which is requesting a large sum or they will pursue legal action in the US against him.

He wants to pay but due to his situation, he is unable to at this moment. They refused his smaller amount of payment offer.

He does not plan on travelling back to Abu Dhabi. The question is, he is trying to pay but they will not accept that amount.

Why will they not take the amount offered since he is communicating and wants to pay? What can they do to him in the US?

How will that help them get their money back?