On the face of it I have no problem with this, but the analysis performed would be limited to fairly mundane pathing around a station. I visited London and some of the stations were less than straight forward to navigate.
But the real juice would be being able to map this data to demographic data, that's where some real valuable marketing analysis could happen. If I were running this system I'd be looking for every way I could (legally) get clues about who you are - not as an individual but as a marketing target.
E.G. if your device checks in with an access point in the men's room, thanks now I have your gender :)