1) The paper more or less ignores the effects of technical safeguards built into modern smartphones operating systems.
2) the paper mentions that the reason why there hasn’t been more mobile outbreaks is that no smartphone operating system is dominating enough. Then in the next paragraph it mentions that Symbian has, oh, 65% market share of all smartphones.
We model the mobility of mobile phone users to study the fundamental spreading patterns characterizing a mobile virus outbreak. We find that while Bluetooth viruses can reach all susceptible handsets with time, they spread slowly due to human mobility, offering ample opportunities to deploy antiviral software. In contrast, viruses utilizing multimedia messaging services could infect all users
in hours, but currently a phase transition on the underlying call graph limits them to only a small fraction of the susceptible users. These results explain the lack of a major mobile virus breakout so far and predict that once a mobile operating system´s market share reaches the phase transition point, viruses will pose a serious threat to mobile communications.