Ramesh Ponnuru of the National Review published a correction of the National Review article, speculating that perhaps Thompson had had a change of heart in 1997.
After researching the issue, his "running as pro-choice" appears to amount to a single quote in the AP and which was interpreted by a Nashville paper to mean he was pro-choice, in spite of a solidly pro-life record; in subsequent interviews that very year, he stated he was pro-life.
So, he's multiple choice?
Is that it?
In that 1997 letter, he says that he doesn't believe that the government should have a voice in an individual's decision to abort or not. That's consistent with both the notion of overturning Roe v. Wade AND with his being pro-choice.