Senator Whitehouse is taking a very strange position. In the hypothetical, even looking past the objections noted above, the girl (or the guardian who bought her the phone) deliberately purchased a secure device and could have chosen a less secure model had they decided that the potential risks of strong encryption outweigh the benefits. When individuals bear the predictable cost of a consumer choice that they made without coercion it is inaccurate to say that the seller socialized the cost.
Of course, there may be hypotheticals better-suited to advancing Whitehouse’s agenda. Say that some radicalized proponents of Herman Cain’s “9-9-9” tax plan plot to blow up 27 water towers in a misguided bid for their hero’s affection. After they’ve planted explosives, but before any detonations, they’re apprehended thanks to a tip from one of their co-workers at Godfather’s Pizza, who looked over their shoulders as they were texting back and forth about the plot. If authorities could access those messages they could save the water towers. But everything is encrypted, and hours later, all the water towers go boom.
The mustachioed terrorists succeed!