Which is an assumption on your part, which you are entitled to make, but no where does Apple say they cannot remotely disable and re-enable the advanced protection.
Furthermore, if the code exists to send the keys to Apple already, who knows what circumstances can cause that code can be activated and send the keys to Apple or someone else.
And no where does Apple say the government does not have access to that code. There are technical ways that can allow the government access to the keys even when Apple cannot. That way their marketing can go full steam ahead regardless of the reality.
You are really overthinking this. I appreciate privacy, especially from government eyes, as much as anyone else, but the reality is they are already able to get around E2E encryption if you're truly a target. The Pegasus flap is undeniable evidence of that. If you think NSO was the only player or even the biggest, that alphabet agencies have at their disposal, then think again. Odds are very good we don't even know of their most powerful tools yet. And if your concern is that a government can remotely deactivate ADP so as to get to your data, you should realize that if the can do that, they already have access to your data right from your phone.
You're never going to stop every attack vector or plug every security hole. Vigilance is good, but it should be aimed at what is truly effective, not channeled to paranoia towards Apple about things Apple cannot control. The fact is that for most users, this is a step forward in terms of security and I applaud the move by Apple to do it. It also highlights why Apple a year ago wanted to scan photos on-device before upload, which I did and still oppose as an overly intrusive breach into peoples' personal privacy.
If Apple can't access your keys, then they can't hand them over to anyone, and it's doubtful Apple has code established to remotely disable this encryption, but time will tell. Even if they don't, someone else like NSO will come up with a way and governments will find ways to exploit it on targets of interest. The only sure way to prevent that is (A) don't make yourself stand out as a potential target, and (B) don't use your phone for sensitive (legal or not) or illegal purposes.
Even if you don't use your phone for those things, utilize the speed bumps at your disposal to protect your privacy because even if they aren't foolproof, they can still deter certain actors based on perceived cost/benefit ratio. Similar to locking your front door so thieves will move on to look for the unlocked door unless they are certain picking the lock or breaking down your door is worth the risk and effort.