Like you were advised its highly unlikely his friends were hiv positive and what he engaged in,this brotherhood ritual,its not a common practise.I would advise testing in this situation.Because its direct blood to blood contact-- binding.At 6 weeks you can receive a good indication of his status and at 3 months a conclusive result.All the best.
Tha'ts very bad news to me.
I thought that only sharing needles, unprotected sexual intercourse or mother to child are the routes of transmission. I'am forced to perform than my first HIV lesson to my son.
Yes,the cuts would have to be deep and cross contamination would have to take place,however it would be highly unlikely that your sons friends would be infected with the virus.