Employing family and friends has pitfalls. They expect everything and take advantage of your kind, helping nature. You might be put out a lot of times doing them favours which they might expect of you being family or friends of yours.
Personally I would rather employ a total stranger and run it as a business as after all that's what it is and run it professionally and run it to suit you and not your friend or relative. If the two of you fall out in time it can cause more hassle than it's worth but that's just my opinion.
I have employed in the past but I wouldn't employ family or friends and I kept it all above board with PAYE, sick pay, holiday pay, accountant, etc.
I don't employ anymore after a life changing illness affected my long term health. Had to give up work for some time, but when I got better I looked at life and decided there are more important things in life than growing a business, so I settled for having my independence, freedom to choose my working hours within reason, together with a happy balance of work and life balance.
I hope it all works out for you both and he gets himself back on his feet with your help.