If every human was now immortal and aged to a 25 year old's body permanently...

>bring a child in to the world?

Well... maybe not the world...

How is that a counter-argument?
Okay, let me try:
"Humans generally have two arms, thus you are wrong. "
Eyyy, this is pretty sweet, I have to do it more often.

Is this with or without the ability to commit suicide?
Can you still die from violence and disease?

take a look at these hands