I would have thought that a mobile telco could generate this data already just from what they need to route data (and voice calls) to each phone, at least to a somewhat coarse level, without needing to have apps upload this.
Yeah, they have to be able to. Something about this story just doesn't add up unless this is explained.
They were after data for other carriers and/or more enriched data than they could easily collect. They could use this data for their own marketing and/or network planning. e.g. “We have the least share in market M where some significant proportion of all cellular users , based on twitter data, love NASCAR and spend relatively a lot of time on their phones at racetracks and Walmart. Lets increase capex around race tracks, do a promo with NASCAR and Walmart, and buy some appropriate ads.”