It's not more secure, this guy doesn't know what he's talking about. It is way, way less secure to store keys in your cloud storage. I would never touch this kind of system.
Discussion
They keys are not just like this in the cloud, it's an encrypted file and it's part of the 3fa secret for the recovery process, so even if a hacker access to the file it's not enough for recovering the funds. it need to match the 2 other authentications
because you didn't open and read the post about ZenGo security or misunderstood it let me post it here:
We’ve replaced the traditional private key with two independently created mathematical secret shares. One share is stored on your mobile device and the other on the ZenGo server. With no single point of failure, even if something happens to one of the shares, your crypto is always safe.
Unlike exchanges, ZenGo cannot access your funds. To send funds, you initiate a process in which the server and device shares communicate to sign the transaction without ever revealing their secrets to each other.
If you delete the app, lose your phone, or want to use ZenGo on a new device, simply scan your face which will match with the 3D biometric face map you created during setup. Now your wallet is restored!
Let me know if you need more information