Not trying to make noise, just being realistic. Also, while the Big Ten may have been aware that Nebraska was at risk of losing AAU status, there is no way that they could have known they would for sure lose it. Nebraska was invited to join in the summer of 2010, the vote to remove them wasn't until almost a full year later. Nebraska had similar circumstances happen previously, and was able to maintain membership, so it wasn't an unfair assumption to think they would be able to survive another vote, especially with all the B1G schools voting for them to keep it.
While the B1G is a sports conference, every member is also part of the Committee on Institutional Cooperation, which makes it an academic conference as well. The presidents of the schools vote on membership, not the ADs or Delany.