LOL @ "slight possibility."
Anything that obvious is probably wrong on this show.
Jesus Christ, the scene is not remotely ambiguous.
Walt is making the freaking call from the sight of a safe haven. He's already decided to give Holly up. He's specifically lying about the extent of Skyler's involvement (which is foreshadowed by the fact that the freaking episode OPENS with him lying to Skyler, which is meant as a piece of thematic foreshadowing). He's crying while making the call. And you can see the visible relief in Skyler's face when she realizes what he's doing.
It is defensible to argue that Walt is using some real deep-seated resentment of Skyler while making the call, but there is no question that he is trying to exonerate Skyler. Walt may be dying. Returning Holly would do no good if her mother is going to be locked up.