Bova is the agency of record for some valuable properties, including most of Scott Card's work. Agents don't just find new authors and sell new books. They also perform various services on behalf of existing clients and book deals. If the agency shut down, it wouldn't be able to service those accounts and the agenting deal would lapse, meaning they'd stop getting their percentage on profits and new deals. I can't imagine them doing that when Ender's Game looks like it's finally going to become a major motion picture.
That said, the Bova Agency doesn't have a lot of incentive to take on marginal clients. My guess is that if something amazing turned up in their submissions, they might take it on, but otherwise they'll just say no.