"All those nasty hackers..."
"If we simply build in this kill switch they might turn us off, but at least will leave the rest of our data alone.
Of course we're not making it easier for them; who would want to use such a scheme to blackmail us? That's absurd. Besides; if they do then at least we got their address. Its a full proof plan!"
Lets talk about in, say, 3 years or so. I can see it now: "Hacker threatens to shut down $small_cloud_provider by pulling kill switch".
They I'll go: "Told you so!".