this is bs.
I wonder what is more likely to be datamined: your voice conversations through speech recognition or your searchable text in SMS/e-mail?
the latter today are even offered as in "free", not that you don't pay your monthly fee, but you can use that to make a voice communications.
Mobile companies are happier if you provide them with sensitive/personal information throught text.
Social/cultural trends are just being extracted from this info, its just google with another name.

Wich reminds me of when echelon scandal broke out some years ago in europe: companies were advised to use PGP/encription in their electronic correspondence. By accommodating the advice companies were pinpointing what was and what was not "sensitive". The effort now was reduced from billions of e-mail to mere thousands.

maybe... I must be seeing too many movies!