I think it is unhelpful to constantly blame the owners.
As the owner of a dog with behavioural issues I am often blamed, most owners of dogs with behavioural problems have actually tried really hard to fix it.
Most of us have spent huge amounts of money, seen trainers, read books, watched training videos and it is really unpleasant to then be told by people it is all your fault, you are ineffective, useless etc.
A lot of a dogs temperament is genetic and should not be blamed on the owner and sometimes dogs don't respond to the training given to them despite what some would have you believe. Different methods work for different dogs and for some dogs they will never be fixed and that isn't always down to the owner.
The OP has made two posts, neither of whichever mention what has, or hasn't been done.
For all you know the OP may well have already been trying hard to fix this.
You are making unhelpful assumptions.
The dog gives no warning, that alone makes it dangerous to live with and utterly unsuited to a home with children.
It wouldn't be so bad if it had been a massively inhibited bite but the dog has actually caused serious injury.
Of course it cannot stay.
I find it extremely worrying that dogs that A) give no warning and B) bite severely enough to cause serious injury are apparently welcomed as suitable candidates for rescue!