The paragraph he quoted notes that Apple does not have the keys.
> Even if you choose to use a third-party application to access your iCloud data, your username and password are sent over an encrypted SSL connection.
So user/pass is sufficient to access cleartext of your data, and Apple definitely has that.
This should be obvious: If there is any way to recover your data when you lose your phone (without using a secret key that is never shared with Apple) then the security is broken.
So encrypt the iCloud backup with a password you say... Except you need a password to get in to iCloud already so how is that any different?
And for the record, Apple stores password hashes, so they don't have your password. Unless you think they are just lying repeatedly for no good reason.
When was the last time you verified the chip layouts for your CPUS to ensure there were no back doors? Didn't think so.
Private keys are different than passwords.
Password hashes are computed server side where the password can be trivially intercepted.
CPU backdoors are a security problem, that doesn't negate the existence of other security flaws. Moreover CPU backdoors are far more costly to implement and effort should be directed first at cheaper/easier weaknesses, like ineffective encryption of data.