No, it doesn't "clarify" anything like that. If google doesn't have phone numbers of some subset of the accounts requested... they will just specify so in their response to law enforcement since it is completely legal and google is not currently obligated by law to have phone numbers of all users of Youtube. Sundar isn't going to prison because of that or anything.
Saying that some PM at Google decided decade ago something like "hey guys let's build a database of our user's phone numbers to satisfy some theoretical future dragnet surveillance request from law enforcement and tell our users that it is for their own security" is actually quite ridiculous conspiracy theory if you think about it.