Disagree.
Look at it with a degree of detachment and heartlessness:
First, despite what TV tells you, its actually very hard to murder and dispose of a body, even a baby's body, and not get caught. It's much easier to leave a live baby in a busy park and not get caught (as Elsa's siblings have proven).
Second, look at the media and public rhetoric. A live baby is found and the news articles encourage sympathy and concern. A baby's body, or parts, is found and there's no such sympathy or concern. So even assuming an equal risk of getting caught, the outcome is likely to be much softer for abandoning a baby, than murdering one.
Thirdly, related to this, murdering a baby is (rightly) condemned by society as wholly psychopathic so there's likely to be little leniency if the person is caught and convicted. But abandoning a baby is (rightly) seen by society as a result of dire circumstances where mental illness, addiction issues, abuse, isolation etc. can be cited (truthfully or falsely) and taken into account when punishment is decided.
That's before you get to the issue of whether a human being could actually, as you said, chop up or burn a baby. I believe the biological father has snatched Elsa from her mother and put her in the park. I believe he's a trafficker and is abusing and raping Elsa's mother. I believe he's an unimaginably cruel, heartless bastard. But even someone like that would draw the line at actually murdering a tiny baby. There is some modicum of care there because Elsa was wrapped and placed in a busy spot.