Margaret Sanger is an often cited example. Her conception never happens in this hypothetical. Other people who supported eugenics- outta here! Racists, sexists, and anyone else who were/are holders of generally agreed upon horrible ideas and actions- no pass for you for holding a position I support!

Now, let's do the same for people of those varieties who happen to be pro-life (their fathers flushed them down the toilet, and their mother's threw the other part of their bodies in the trash). In addition, any currently pro-life person who ever had or performed an abortion or coerced someone to have an abortion are gone. Any pro-life person seeking to limit, ban, or mislead about/discourage contraceptives is gone. Anyone unsupportive of programs that increase the quality of human life is gone. Any pler making an utterly ignorant (by the most charitable interpretations) "explanation" of why they have anything worthwhile to say about human reproduction in the same ballpark as:

https://youtu.be/X5W8nCN8Cc8

Never conceived!

TLDR; pro-choicers can police their own and should. Plers doing likewise would be a complete de facto surrender to individual female humans the world over that each of them and all their female descendants are fully human persons and free to make medical decisions for themselves in practically uncontestable perpetuity.