DoomFreak

This has nothing to do with sexually exploited children.  That is the rationale they use to invade citizen's privacy.  There is no such thing as a back door that is safe.  If the government can get in using it, so can/will others.  They will wind up with a worse problem than the one they are trying to solve.

In the spirit of being open .... we will threaten developers for trying to be open.

I think throttling the phones was the right idea.  They are trying to protect the battery.  The battery ages and needs to be protected.  The battery is not easily replaceable, so it would be cost prohibitive to replace it.  You might as well get a new phone.  So which would you rather have: a phone that goes a little slower, or a phone that is broken.

Apple asked about Mueller team members who wiped iPhones

Department records showing that several members of Mueller's team wiped their iPhones due to "forgotten passcodes, irreparable screen damage, loss of the device, intentional deletion or other reasons."

But then you later say it is routine to wipe phones when they are returned... Why did they not just say that as their excuse?

Also there is a difference between wiping the phone and wiping the iCloud data.  Those are two different things.
I don't think that any investigative branch destroys any evidence.  Such a practice would be very unusual.  Rather, it is a practice to keep evidence in perpetuity.  It is not uncommon to have storage rooms full of it.  I don't think that digital data would be any different.

I would hope that Apple would never open up default messaging to Facebook.  It seems contrary to its goals of creating a secure and private environment for its customers.  If someone wants to use that crap, let them.  At some point you have to protect people from themselves though.