As for him bonding to you he will bond with someone else. I foster dogs for a rescue and some of the dogs are in our homes for months at a time (whether it is heartworm treatment or just haven't found their people yet) they still bond with their new owners. When they come visit us at events they are happy to see us but they have moved on and are more bonded with their new people.

speaking from the veiwpoint of a shelter worker, it is in the dogs best interest to return the dog BEFORE there is an incident! I know you are doing evrything to prevent that but nobody wants a dog that has bitten a child as opposed to afraid/not good with kids. Being a no kill is good and im sure he will find a good home and be taken care of while hes there, he may even prefer it to being around kids which make him nervous. People feel bad for the dogs at our shelter but they actually get more love and exercise and training than most peoples pets....maybe thats the case there, I have no idea...just trying to make you feel better

Also we will not adopt a dog to someone with kids if they wont be good with kids even if that person insists they will be fine or can handle it...we've had a lady want a dog which had bitten a child and she had kids...sigh. While admittly we roll our eyes when people surrender their dogs b/c they are "having a baby"...we would never make someone feel guilty for returning a dog that was this agressive with their child. It was the shelter mistake not yours and you did more than your part. Do not feel guilty, imagine how much worse you would feel if the dog bit a child, and then that makes the dog nearly unadoptable as well.

Best of luck in all of this, I hope things work out for you