allthree what support strategies has your early years settings put in place to support the child? Its all fair that you are concerned and asking here. You will get some excellent pointers from the members here. You must be a very rare nursery worker who cares so much for the child. Like Kleinzeit said, I would like to have a TA like you for my child. 
However, as a parent of a child with special needs, I feel that the child in question and the other children around him are being failed at multiple levels by a setting where parents send them by paying their hard earned money.
If you are his key worker, have you raised this with the SENCO and nursery manager? Have you discussed this with the parents? Every setting gets a certain budget to put support in place for children who need that. Are these sensory issues? Was he hungry? Did he have a way of expressing to you and his peers that he is upset that the toy has been taken away from him? Has he had any training of sharing toys? Does he have a diagnosis? Has the GP and local child development center seen him? Are these incidents documented so that they can be used later if needed for diagnosis and education support?
What was the reason and purpose of his behaviour?
Honestly, if I was the parent of this child(and last year my child almost reached a point where she would hit the staff because she was so frustrated and she had no means of expressing herself, let alone engaging in anything useful
) I would take him out of this early years setting ASAP and start my own intensive intervention(which is what I did with her, till she reached a point where she could modulate herself to some extent and has 1-1 support in place).
I am struggling to express, how I would react if I was the parent of the child that got bitten 
Its not your fault.. the settings' management need to belt up.
Swanhildapirouetting - Golden words you cannot react to behaviour, you can only prepare for it when you have an autistic child.