If you read the whole announcement, the business is not just to buy, hold and give access to their Bitcoin treasury, they intend to build financial software that uses Bitcoin underneath:

"Twenty One is structured to be a day one Bitcoin-native company that will strategically allocate capital to increase Bitcoin per share. Twenty One intends to develop a corporate architecture capable of supporting financial products built with and on Bitcoin. This includes native lending models, capital market instruments, and future innovations that will replace legacy financial tools with Bitcoin-aligned alternatives. As a pro-Bitcoin advocate, Twenty One plans to produce original Bitcoin-focused content and media. This pure-play approach will offer investors access to a public company that combines Bitcoin exposure with an operating business building Bitcoin-native products and services."