If the stand is extended, when the bike leans over on the stand the weight engages the locking tab.
The bike is not going to fall over. You can drag the bike all over the parking lot and the stand won't collapse.
Just to give yourself peace of mind, while the bike is on the stand, and yes, in the Harley world it is referred to as a jiffy stand, try to push it backwards or forwards. Unless yours is defective it will not fall over.
As mentioned, once your bike is on the stand, you can rock it back and forth as much as you like and it won't go anywhere. You can even park it on a slight downhill if you want.
Just make sure your bike is leaning downwind in strong winds though.