Earlier quoted context omitted.
This is a tangent within a tangent, but it's basically a political strategy. Abortion bans are deeply unpopular, even in many Republican-majority states. By framing it "after six weeks", they're attempting to project the image that they're the reasonable ones. After all, women would have had six whole weeks to make up their mind! And it will allow an escape hatch for women in rape or incest situations. As a practical…
Why are politicians trying to pass a law that is, "deeply unpopular?" Do they want to lose elections, or something?
That is an interesting question which may have something to do with Game Theory and Prisoner's Dilemma. Even though Republicans as a whole will lose votes because of this, each individual Republican candidate will stand to gain an advantage over their primaries rivals by being perceived as more uncompromising, more principled.
And it is curious if not silly, 6 weeks is seen as, conceived to be "more principled", than 7 weeks.