I think one aspect is that it relates to a reason for abortion in cases where the child has been identified as having a severe disability which will cause it suffering when it is born. I remember a doctor suggesting that spins bifida could be like this.
Many people who would not otherwise agree with abortion might do so in a case if such a disability were going to severely affect the baby, yet they might not feel at all sure about ending the life of a child once he or she had been born. Logically though it should be the same as abortion.
I am not sure what I personally feel about the euthanasia in the article. On the face of it, the child’s suffering was so bad it was a certainly mercy to end it. It must have been truly terrible for the parents to have to make this choice.
On the other hand, I feel unease that this sort of euthanasia could be abused and used to end the life of a disabled child whose life might nevertheless be worthwhile for them, and have quality and purpose - but be inconvenient.
But balance I agree with the practice a pp mentioned as being relevant in 1970 when the pp was born, which was to have the choice not to take steps to keep a chid alive just after birth if he or she is certainly profoundly disabled. That is similar to the OP article though more passive and less active.
It must be so upsetting for any parents having to consider this.