The car will not "propel itself forward", it will very slowly start moving forward. I know that very well, since I normally drive a stick, and when I sometimes drive a rental or a borrowed car, I sometimes forget and take my foot of the break while waiting at a red light. One time I actually fell asleep and bumped into the car in front of me, but the spped was so low that the driver in front of me barely noticed, and I just barely woke up.
Other than that, though, he actually mentions "vehicle in drive", so he assumes automatic. I have my vehicle in neutral while waiting on a red light, and if I am on a slope, I even have my parking break on. I doubt that he would take that into account when issuing a ticket, though.