I can only assume that, if he has a ccj, all of his credit will have gone bad and probably be with debt collectors or indeed the court. On that basis, if we assume that he is paying his regular payments, then it is highly likely that there is little or no interest being added on an ongoing basis.
The question would be, therefore, why a loan would benefit him. The answer is that it wouldn't. Firstly, his original debt, even if such a loan were possible, would automatically increase his total indebtedness, 60 times 200 is 12000. Secondly, at 300 he will clear his debt, at £300pm, in 33.3 months, not 60 months. Thirdly, his credit rating will not improve by taking such a loan in the first place. Fourthly, what happens if he suddenly finds himself in a bad place again and cannot meet the repayments? Poor old Mum and Dad saddled with the debt. There are no winners in this scenario at all, far better to let him pay the debts back as they are in my opinion.
Regards.
