If they start allowing YouTube to work with the PiP feature on iPads (which it always could with third-party workarounds, but not in the official app [1]) after this, then it'll be confirmed that they purposely disabled the feature on iOS only to retain artificial parity with Android, which would be a very scummy behavior.
[1] https://www.reddit.com/r/apple/comments/5lxm6c/why_is_google...