"So the question is actually what is worse: destroying the kids lives through sexual abuse or insane law enforcement?"
There is no equivalence in this case. Sexting is not "sexual abuse" and the potential for long-term harm to minors from sexting is far less than the harm from being forcefully dragged through the legal system and coming out the other side as a registered sex offender.
"any encryption that's protected by a five digit pin is not secure."
On it's own, you're correct, which is why Apple built in the very safeguards the court is now trying to force them to disable. It's almost like you haven't read any of the many articles explaining this...
Of course it's also possible the dead user of this particular phone felt the same way you do, and didn't keep any sensitive data on the phone. That's what makes this such an over-reaching fishing expedition. The potential downsides are enormous, but it might well be for zero gain.
"The problem is, in the case of an actual active-shooter or hostage situation, restraint is really the last thing you want them to show."
Fair enough, but first they should have to determine if there really is an actual active-shooter or hostage situation. Until that's decided by professional LEO's, not unreliable or malicious "witnesses", restraint should absolutely be shown.
Given their history, any strong pro-IP stance from Metallica is totally believable. Lawyers act on instructions from their client, not on their own whims. Somebody either told them to do this, or (more likely) they had standing instructions that weren't clear enough in their limits. The band may honestly not have wanted this to happen, but they're not blameless.
"Would you ever argue that a grocery store with record sales shouldn't worry about shoplifting? I wouldn't, because it's a silly argument."
Well that's exactly what a lot of stores do to a degree, so who's the silly one?
"Yes, it's a successful film. But how successful would it have been without piracy?"
Wrong question. The right question is, how much more or less money would we make if we stopped heavily investing in historically unsuccessful anti-piracy efforts, and put that money into productive (i.e, profitable) areas instead. Given widespread piracy still is, the return on investment seems pretty terrible. If you could make more money overall by taking a more realistic approach, i.e. targeting only large-scale commercial piracy instead of the general public whose custom you're trying to win, why wouldn't you?