According to the pic, the handles has to be pulled back to idle, then to reverse, just past idle. Is there a safety built in? I dont know, but I dont think there needs to be. The FBW computer should keep the reversers from deploying unless the engines are idle and/or the ship is below a certian altitude.
If you look on the 2nd photo of the original post you can clearly see the reverser switches about halfway down the front of the throttle. They are flat and pointing forwards. It might look to some like it's on the throttle quadrant between the levers but it is the reverse switch for the starboard engine.