Strava is a fitness app. So, apprently, the security detachment of political figures tends to use the app, presumably because they're into fitness and keep in shape, and their location can be tracked through the app.
As the security detachment tend to travel with the people they protect, political leaders locations can be inferred.
The article talks about body guards not being allowed to use social media/apps while on the job, they allow for provisions on use when not on active duty. So, I guess, the guards get a day off, use the app, wherever they are, broadcasting their location.
Crazy stuff.