I don't think there's anything blithe in pointing out that an after-the-fact promise of secrecy serves no one.  Affiliates had to decide whether to vote without knowing whether the list would be published (but hopefully realizing that the username of their voter would be published, although I'm not sure if this was made clear).  The main effect of post-hoc secrecy here would be to sow confusion and set up unrealistic expectations about future votes; in the last affiliate-selected board seat process, not only was the list of voting affiliates published, but their individual votes were as well: <https://commons.wikimedia.org/wiki/File:Asbs_presentation_matches_with_stv_py_results.pdf>, and for the reasons Lodewijk describes, we might well wish to return to such full transparency in the future.

If a decision either way had been made and communicated beforehand, affiliate voters could have made an informed decision, but as with most of the rules for this election, it was announced in the middle of the election, rather than in the many months before it.  In any event, I agree with SJ that this is a decision to be made by the elections committee, not WMF staff.