But in order for Google to catch people spying on other people by viewing their calendars, Google would have to surveil the activity of the people doing the spy

But in order for Google to catch people spying on other people by viewing their calendars, Google would have to surveil the activity of the people doing the spying. Maybe that's what the headline is referring to, but the article doesn't spell that out explicitly (which makes it a very poor piece of journalism in my opinion).