I think he's having trouble because he wants to get it all at once but tell him, he needs to take time and withdraw it slow and little by little with small amounts that won't remove him from that aid program.
The problem here is that he needs to justify where he got such amounts, small or significant, since it will come through an exchanger account. The bank or the gov can ask at any time anything related to it.
That's kind of tough for him if that's what he'll get even with small amounts. I am not oriented with such policies there but if that's how strict they are, he needs to be careful or else he'd say goodbye to that program and benefits. How about going to the next country that's just beside Germany and he'd do the transaction there. Will there be concerns about him getting some cash there or withdrawing it from another bank outside?