Not sure why conservatives continue to downplay JMcC’s good pro-life stance. The perfect should not be the enemy of the good
Very predictable piece of human nature. The more a person has invested his personal involvement in an issue, the narrower the range of acceptable positions on that issue. Extremists will have only one pinpoint position--their own-- and everyone else's will be lumped together and indiscriminately distorted away into the unacceptable outer darkness.
This is classically illustrated by the purists who say "there is no difference between McCain and Clinton." Of course, there are large differences in reality, but to the extremist the differences are insignificant, meaningless, and may not even be perceived.