[gumby]

But private actors can't easily map IMEI to user. Law enforcement typically can but the article doesn't suggest he's trying to defend against them, just private actors.

Sure, individuals in law enforcement or the phone companies can be suborned (i.e. bribed) but all the procedures procedures described in the article are part of "defense in depth". And in fact some of the others make it harder to even know which IMEI to track. I don't know the IMEIs of the handsets of any of my friends -- or even my own, though I could look it up.