I would pay it off. I believe with Covid there is 0% interest until the end of the year, not sure if that is only for direct loans or if it covers Perkins loans as well.
It’s not worth messing up his credit if he wants to buy a car or get an apartment in the future.
If he had loans, he had to do exit counseling and that should have explained the repayment obligations and repayment starting after 9 months, once he was not in school at least half time. Has he received mail or email from them in the last three months?