The decision to be made was “will you support ANY of them?” For Brownback, the answer, for his own purposes, turned out to be “yes.”
Any cooperation with evil, except to avoid an even worse, otherwise inevitable evil, is culpable. So Brownback needs to explain what worse alternative he avoided. Given that the pro-life faction is the minority we know in fact that there would have been no alternative, just a one-vote difference in her confirmation approval vote count.
Brownback risked alienation of the apathetic majority, on the abortion issue, people who do not like “single issue” politicians.