After the Pegasus news that showed that a relatively small private company in a very small country could have complete remote access to your phone and sell it on the market, do you really think that a powerful government like China or the US can't already do it??? How could you be this naive? Especially after the Snowden revelations.
And about Apple's having a change of hearth in the future and using something like this against you. Have you stopped to think for one second and consider that they have complete control over the updates that your phone receives?? They can quietly do what ever they want without you ever knowing and you can't do sh*t about it. So drop the concerned citizen act. We all abdicate privacy a long time ago when we sold our souls for cool free services like google and sexy gadgets.
At the end of the day the "slippery slope" argument boils down to one thing: do you trust your institutions? Any law or service can be abused, and the only thing preventing that is the integrity of the people on your society and the institutions both public and private that they work for. The exact same law that is used to fight corruption in a great country like Norway or Denmark can be abused to persecute political opponents in a shitty country like North Korea or China.
If the answer is no, I don't trust my institutions and my people, then you have a far more severe and fundamental problem than an specific law or service. In that scenario, focusing in an specific issue is like trying to cover the sun with your hands.