But you are correct; the fetus is not "as" affected.
However, considering it takes only ~8 minutes of oxygen deprivation to render a person brain dead, seconds clearly matter. So the baby is what, 7 minutes, 6.5 minutes without oxygen? Severaly disabled as opposed to a functioning brain stem?
Why should the father AND his living son have to bear the burden of our scientific experiment?
Sure, the child's rights don't necessarily outweigh the parents'
Yet that is exactly what you are arguing.
The mother didn't want to harm her living family by forcing them to bear the emotional, physical, and financial burden of her being kept on life support. That is her right. You are saying the unborn child's right is superior to her right, so it should be able to OVERRIDE the mother's choice and use her body.
As next of kin, the father has the right to determine whether he wants to bear the emotional, physical, and financial burden associated with keeping his dead wife on life support, and whether he wants to place his living son's future at risk emotionally, physically, and financially by accepting the responsibility for a possibly (likely) disabled child. You are arguing the the unborn child's rights are superior to the father to the point it OVERRIDES his right to make that decision.