"You shouldn't use them, because of the software, but also, because
    your cell phone is a tracking device, even when it is turned off,"
    Stallman said. Interestingly, in the minutes before the talk began,
    Stallman padded up one aisle in his stocking feet talking into what
    looked like a mobile telephone.

I don't carry a mobile phone, but I don't see anything wrong in
borrowing one from someone to make a call.  In the same sense, I would
consider it wrong for me to have a machine with Windows on it, or to
use one regularly, but I see nothing wrong in using someone else's
Windows machine for a few minutes.

I don't think the words quoted are my exact words.  Reporters
often change quotations.