Siri returns all my colleagues' Google calendars even if they are hidden

We use Google Calendar from Google Apps for Business at my office, and through Google Calendar, my coworkers share their calendars with me (I do an "Add a coworker's calendar" in Google Calendar.)

When I add my Google calendar account to the Calendar app on my iPhone/iPad, it will also allow me to display or hide my coworkers' calendars. I usually keep them hidden.

When I ask Siri what my schedule for the day is, Siri's response includes all my coworkers' schedules and not just my own, even though I have them hidden in the Calendar app. If I go to the Calendar app, the coworkers are still hidden. If I click on one of my coworker's meetings in the Siri response, it takes me to the Calendar app, with that coworker now unhidden.

What I would like to happen is that Siri not return my coworkers' calendars when I ask for my schedule. At the very least, don't show them when they are hidden in Calendar.

Is this a known bug? Feature? Does anyone else have this problem? Any workarounds?