For instance, in airplane mode with no network access iPhone response to 'Hey Siri' is 'Siri is not available. Connect to internet'
Prove it. Seriously, don't speculate like this until it's proven one way or the other. Prove that it violates my privacy and then we will talk.
Why don't you "prove" that all the metadata is not used for commercial purposes, and that metadata isn't available to government agencies.
I fail to see how this is any more a possible privacy breach than my iPhone that's laying right next to me right now.
The probability that my privacy was compromised by a mandatory court subpoena is very low, hence the person used "rarely touched privacy".
Premising your argument about government agencies all over the world is argumentum ad absurdum.
You made the positive claim, you are the one who needs to provide evidence. Until you do, a rational mind is well justified in disbelieving your claim.