If they allow phones at all, then the threat cannot be an issue of a passenger sending a command out of one of these. The threat has to be the device itself.
Now, a standard issue iPad is no threat, so we're talking about a customized device made to look like on.
Except, if terrorists are going to the trouble to do this, they can just as easily put whatever bad thing they want to put into the case of an insulin pump, and bypass the ban.
This. Is. Bullshit.