Not exactly a neutral audience, though. A number of people following the account, if not most, will be following because they share the same sense of humor. Likewise people @ed by friends.
You cannot be sure how quickly your colleagues will respond to messages when you are absent, so avoid promising any instant assistance. Moreover, ensure you take permission from your co-workers before giving their details in the message. They might be too busy to substitute.

Before I implemented this system, I got *way* too many calls asking if so-and-so was out of the office that day when an OOO tells them that Bob will be back in three hours and to call Sue in the interim. The OOOs have reduced status check calls to practically zero, and the OOO preview pops up in our system as soon someone’s email is entered.
Yes, I phoned a dentist office late in the day for a reinfected root canal problem and got a cutsy “humphrey bogart” fake reply on their voicemail — I thought it was extremely inappropriate for a business office to use something like this. It was hard to find it funny, especially because while calling me “sweetheart” and all that, the message didn’t actually tell me when they might return my call (later that day? Next day? Next week? Never?) nor did they offer any options for emergency contact with another dentist.