I'm not sure I completely comprehend the issue: so you want to play a location-based massive multiplayer game, AND you don't want to let your location be known. Hmmm.
Why can another player retrieve my current location just because I posted a chat message?
This information is not displayed in the game, but the data is retrieved.
Every time the event list or the chat is loaded, along with each post content the location of the player who has been the source of the event is also coming from the server.
It's not the current location that's retrieved. It's the approximate location of when you sent the message (or as I mentioned previously, the location of your map view in intel if you send the chat from there) or other "alert" event.
Considering most of the alert events are location specific events (playerX captured/attacked/deployed portalX, linked portalX and portalY), playing the location based game exposes your location to other players.