I wouldn’t be surprised either - I think he was just wanting her to serve a few days, not become a hostage political prisoner.
The plaintiffs and the ACLU asked Bunning not to jail her in the first place because they didn’t want the negative optics of a middle-aged, white woman jailed for her religious beliefs.
Now that the marriage licenses are flowing, Bunning has no reason to keep her. I suspect the LGBT nazis put pressure on him to stop the damage to their cause.
There are reports on Twitter that Davis will refuse release. They forced her into custody; They can force her out.