Why should it be opened to them - LE obtained a search warrant LEGALLY for it...that is why. Pretty simple and I am sorry you can't understand that. No different than a search warrant for your house, car or any other personal affects you may have. They do this for computers already, again, I don't have a problem with that.
As for your experiment, don't they do that with DNA already, can't get any more personal then that. If you don't offer it then they just get a WARRANT for you to supple it or they can take it forcible if you refuse. Again, I don't have a problem with this.
Yes, there are times innocent people get that get search (legally), lose their privacy for a moment in time, but if they catch the bad guy more times because of it, I am ok with it. I can't say it's happened to me, and I can't say I won't be upset if it did, but if they could have stopped someone, but couldn't and then that someone killed my grandkids, kids, etc, then I would be more upset at that, then them searching me, my phone, my car. **** happens, we live in a Fd up world.
BTW, if a criminal wants the content on your phone, they are going to get it, one way or another. just like your house, car, etc. People are just too damn paranoid.
Again, I understand your point, but you missed mine completely or you just completely object to a justice system.