This isn’t an apology. An apology would consist of replacing the head of the organization.
Since they didn't do what most are accusing them of, it is difficult to write that into an apology.
The Girl Scouts did not endorse Wendy Davis. Neither did any official spokesman or any tweet from their account.
What they did do was link to a HuffPo story talking about women of the year and who should be nominated. Someone NOT affiliated with Girl Scouts spoke of Wendy Davis in the article. It was not an article focused on Wendy, but many different women. The one mentioned most was youth activist Malala Yousafzai.
http://www.huffingtonpost.com/2013/12/17/women-of-the-year-2013_n_4461327.html?utm_hp_ref=tw