I hate these type of cases where parents won't accept the reality of the situation. The NHS does not have limitless resources, they would not be suggesting that treatment was withdrawn if they thought that he had a chance of recovery.
My beloved grandmother died last year, she was very elderly but they treated her initially as there was a chance of recovery. Treatment was stopped at the request of the family (we had an LPA) when it became.clear she has suffered a serious stroke which rendered her immobile on one side of her body and unable to speak, she would have had no quality of life whatsoever (she was frail and also had dementia). I found it horrific seeing her so unwell in the hospital bed and it still upsets me when I think about it.
I've long been a proponent of euthanasia with relevant restrictions and I wish my grandmother had been able to have a peaceful death rather than slowly drowning on her own spittle which us what happened.
In similar situations like the Charlie Guard case where the family want a new experimental treatment I think they should have to fund it themselves. The NHS just does not have the money to pay for all of these unproven treatments.