As someone with an Ohio CHL, I have to point out two things about your post that are not entirely correct.
First, Ohio does not have a "stand your ground" law. In Ohio you must attempt to retreat from a confrontation (if it can be done without endangering you or those with you) before you can use deadly force while out and about in public.
What Ohio does have is "castle doctrine" that applies both in your residence/ dwelling/place of abode AND in your vehicle when you are in it. So you do not have to retreat from your residence or your vehicle when an attempted invasion is made, and you have the legal presumption that the person or persons attempting to invade your home or vehicle are there to inflict death or serious injury.
That is a subtle but very important distinction. In any case, things here are looked at with the "reasonable person" standard using the knowledge and information available to the person using deadly force in self defense at the time of the incident. As always, your ability to articulate the reasons why your were in reasonable fear of death or serious injury and your reasons for not being able to retreat safely (or attempting to do so and still be under fear of attack) are key.
Second, the CCW law brochure you linked to is quite old, as there are items in there that are no longer part of Ohio law. One such item is the requirement to either carry a handgun openly or to lock it up while driving. Such is no longer law and you can dump your handgun in the center console or glovebox without locking it while you drive, or you can just keep it holstered and concealed as is the norm everywhere else. Another item not in that brochure is that you can legally possess a concealed handgun on school grounds when picking up or dropping off a student so long as you do not leave your vehicle.
In this particular instance there are several reasons why it might be appropriate to draw down on someone who verbally threatens to take your money while in your car at the ATM. The robber being right at your window and able to reach inside with an unseen knife or pistol is one, inability to rapidly drive away (vehicle shut off) is another, and having children in the car is yet another one (I am not giving anyone the chance to carjack me with my child in the vehicle).
Definitely calling the cops to report the incident is a good move for the many reasons others have given.