The logic is impeccable.
Many people, however do not like to be forced to see things in a logical way. If they did, they would also have to accept that abortion also “guarantees” entry into heaven and therefore women who choose abortion are acting in the best interest of their “children”.
Moreover, if they accept that their act is a mortal sin, and abort anyway, they should be considered saints for putting the best interest of their “child” in front of their own salvation… sacrificing their own salvation. What could more noble than that?
But I do not think that this line of thought - no matter how logical it is - will be accepted by most people. Actually, I am sure that tempers will flare, and I will be condemned for my logic.
On a more lighthearted note, here is an old story:
A missionary goes to a simple tribe, and tells them about heaven and hell. He tells them how should they behave if they want to get into heaven, and what should they avoid if thet want to escape hell. A tribesman asks him what would have happened if they never heard about Jesus, and heaven and hell. The missionary answers that they would have been in the state of invincible ignorance, and they would have gained heaven. Then the tribesman asks:
“So why did you tell me all this?”.