Yes the thing you are referring to is called a tail stand, and yes it is to prevent the aircraft from tilting backwards, which is especially important on the ATR, because the PAX door is at the back of the plane.

I almost crapped my pants one day, because they started to board the passengers before loading the cargo (which is up front) and the nose started to come up.

I heard stories of ATRs at Eagle taking off with the tail stands still attached and losing them enroute