Why not? I don't think insinuating oneself is a fatal condition. You certainly wouldn't kill him for that, would you? It isn't a valid reason to kill a person who is just an inconvenience.
Mind you, I'm on your side here. I don't think abortion is right in such cases. Just...well, curious.
As for "I don't make ethical decisions based on what-ifs," you ought to try it occasionally. Socrates (a notoriously inconvenient person) recommended it.
I am somewhat amazed that you would consider a man who rapes your wife and then tries to gain access to your family and your families assets on the specious legal grounds that he's the father of the baby to be "an inconvenience."
There is no need to consider the "what-ifs" of every conceivable consequence of your actions if you simply recognize 'what is' and act appropriately. The reliability of cause and effect makes doing the right thing the best thing in all situations no matter how it 'seems' to turn out. The shaky thinking in your example is probably the result of taking "thinkers" like Socrates seriously.