No. That's not the point. The point is that they need a warrant, because there is this annoying little thing called "the Fourth Amendment", see? A phone not connected to the network, or not powered on, cannot be wiped remotely. Even if it could, it doesn't matter, though. Do you want to take a guess why? Well let me tell you. It's because there is this annoying little thing called "the Fourth Amendment", see? Someone could move evidence while a cop is getting a warrant. We still don't say: " Why not ask the judge for the warrant? because it could be too late by then.". And do you know why? Well let me tell you. It's because there is this annoying little thing called "the Fourth Amendment", see?
It actually isn't really very complicated. In the last twenty years or so, the powers that be figured out that the average Joe Six Pack has no understanding of the law or these issues. So they continually try to claim that there is magic pixie dust in the intertubes that causes the ... wait for it ... annoying little thing called "the Fourth Amendment" to cease to exist in the particular location which it happens to be at the moment. It is the standard of adding " ... on a computer" or "... using a computer" to the end of a scenario, and then claiming that it is now a completely different scenario. For example, if a guy robs a bank with a gun or a computer, he robs a bank. But we gots ta have a special law for the guy who does it "... using a computer"! Why? Because it gives U.S. another chance to take a bite at the same apple.
Seriously, the DOJ should change their name to the DOI (i.e. Department of In justice)