Most people can see through a disingenuous person's argument.
But, many are also swayed by that person's rhetoric.
The author lacks integrity if the Means of the argument require ignoring the intent of the Ends. In this case, arguing that the Constitutional support of Roe v Wade is baseless (the Means) so that you can ensure the "life" and "soul" is protected (the Ends).
At the core of the debate about Roe v Wade is the definition of human life and if there is such thing as a soul.
If your position is that a recently fertilized egg has an actual "soul" and is "alive", all further arguments are disregarded. This requires a religious belief system.
If your position is that a recently fertilized egg requires the support of a functional womb for a number of months before it can live on its own, and that there is no such thing as a "soul", then there is neither a "life" to be considered nor a spiritually relevant thing involved.
I'll maintain that ignoring the integrity of the Means in order to achieve the Ends is a fundamental evil.