Reading that part of feature on their website gave me an impression that their 2FA didn't work like what you think. The 2fa didn't work to secure CPLAY app and its "content", it rather works as a competitor to google authenticator, as an --if we borrow your words-- "out of band" security layer for other app like binance and coinbase. What I don't know is... if it'll works. I am rather sure they'll need binance and other app's agreement and cooperation before they can make their 2fa comptible to act as the second security layer of those apps. What I further didn't know is... if people would prefer their service to google's. I myself find it hard to see why I would trust them over google, especially with their performance to maintain this thread
Google is an established brand while rest are new entries in the market. 2FA is a good thing to integrate in your system to enhance the security and give feeling of comfort to your clients. If they are going for an agreement with binance for 2FA, I dont think there is any problem in such move?