Uh, the whole point of code signing is a checksum — it's valid only for an exact match to the original executable that got signed. If it changes, the checksum and code signing become invalid.
That's the only reason they even created it.
That's the only reason they even created it.
But it doesn't indicate that the application has undergone Apple's review process. For that, you'd need a separate signature, signed by an Apple-owned private key rather than a developer key.
I'm not actually advocating this, just pointing out that it would provide the same security as the review process does now, without the need to download apps only from the AppStore. And so ... Apple's "but the security" argument is rubbish.