We don't know from the article whether the women was childfree by choice or childless by circumstance.
Whilst using a fictional child with leukemia might not have been ideal, maybe the truth wouldn't have conveyed how she actually felt quite so well. What she might have correctly said was
"After surviving cervical cancer in my 20s i was rendered infertile"
"My one child was still born, my relationship brokedown and I never fell pregnant again"
"After a decade of IVF I had to concede I would never have a child of my own"
"I wasted my fertile years being strung along by some prick and missed out on being a parent"
To that women her grief at being childless is going to be no less real. So she might have just gone with a short, succinct, shock value lie to convey how she felt.
Equally she may have been childfree by choice and sick of listening to someone else's child on a game console, who didn't really think through the significance and insensitivity of what she was saying.
Who knows.