I'm a little surprised that they would do this. It seems an expensive, and potentially dangerous position for the University to take (relating to conferance affiliation, NCAA relationship, etc) when the petitions aren't forcing the U to use the nickname, they are just putting the referendum on the ballot. After all of the expense to move away from using the nickname, to practically volunteering to go back when it's not required seems a bit surprising to me.
One explanation that makes some sense, then, is that University officials really didn't want to get away from using the nickname in the first place. That's a bit surprising, but possible.
OR, perhaps they want to start using the nickname so that voters, pre-referendum, might get to feel some of the wounds of continuing to use the nickname in a "hostile" environment. As I type this is sounding more plausible. Let the supporters see some of the consequences before they vote to make this permanent.