I worked with a child who bit, about 20 years ago. He was 4ish, had delayed speech and I'm not exactly sure about his home life but his mum had quite severe MH problems and was struggling to cope with his difficulties and behaviour.
She was attending a course to do with her own problems and I was enlisted to help out at the creche by focusing on the child because as soon as the creche-worker's back was turned he would bite one of the other children, on the face or arm.
I literally watched him like a hawk but also played games with him, or with him and the other children, got him to run about a lot as he had energy to burn and this really helped his mum when she took him home. Some of the other parents had been understandably upset that their kids were getting bitten and some did say bite/punch/kick back but we didn't allow this. I came in a couple of weeks into the course.
It may seem unfair that he got 1-1 treatment but the other kids were fine with that, I tired him out, built up some trust. We were playing one day and he accidentally kicked me in the chin. I asked him to kiss it better and the creche-worker said "He'll bite you!" which REALLY annoyed me - he didn't and he didn't bite any of the other kids while he was getting the attention, he didn't even try.
I don't have any in depth analysis of any of this (and am not relating it to your GS, OP) but he was a lovely boy and I really felt for him as he obviously had particular needs and issues with development, home life etc and really bloomed with some positive interaction. It still upsets me to see small children described as 'feral' or 'animals' (not here, elsewhere). I do have a child of my own and he has been bitten and bitten himself - it needs addressing but ALL kids' wellbeing is important including that of the 'biter'.