Hopwin, you'll have to excuse me for not including my reaction to every scenario (probable or highly improbable) into a post in order not to make it appear "black and white".
However, since you're not trying to be offensive
(for the record, I didn't find it offensive, just an attempt at a "gotcha"), I'll humor you. I'm not going to make it a habit to address every fantastical situation someone can come up with in detail.
In case my wife stumbles upon this, no I don't have a son, honey. That said if someone were to be stealing a penny from say, my three year old daughter, here's how I'd process it:
1) I have to assume that the person is a stranger.
2) I'll have to assume I'm not psychic and don't know that this person's intent is merely to "steal a penny".
3) Since my daughters aren't in the habit of waving a penny around I'll have to assume it's in her pocket.
3) This person would either have to be in my home, or somehow have approached my child in public, having first gotten past me.
4) My reaction to a stranger in my home accosting my child, or not, will be very decisive: Whatever is required to remove the threat.
5) I'll assume it's in public.
6) My reaction to a stranger accosting my child in public, by attempting to reach into her pocket, will be very decisive: Whatever is required to remove the threat.
The simple answer: no I wouldn't use the "same level of force", because the "same level of force" would not be required to remove the threat.
Not to mention the fact that I'd be averse to shooting someone in such close proximity to my child.
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"Dress cops up as soldiers, give them military equipment, train them in military tactics, tell them they’re fighting a ‘war,’ and the consequences are predictable." —Radley Balko