Your undersheriff friend needs to research the NY State code. NY law has no provision for open carry. All carry in NY state is concealed carry. I think the only time you can open carry is while hunting or target shooting, but perhaps there are other exceptions such as hiking or fishing. I've never checked since I don't intend to open carry. Open carry when outside on your own property is problematic; if you are in sight of a road or another residence you might have some difficulty.
An unrestricted permit is a permit to carry concealed anytime and anywhere it is not otherwise specifically forbidden (such as in Federal buildings or schools). Most of us with NY carry permits have recreational restrictions, which means the issuing judge has decided that outside of our own residences, we can only carry while hiking, hunting, or at the range, or traveling from home to those types of activities. The restriction is administrative and does not carry weight of law, meaning that someone carrying outside of his restriction cannot be arrested and charged with a crime, but the issuing authority could revoke the permit. Not so for open carry; you could be arrested and charged with "menacing", which could be a misdemeanor or a felony, depending upon the situation. Not a good thing.
Hope this answers your question. You can Google search the topic and get a lot of information (some of which is valid). YMMV.
I don't think I would be charged with menacing.....
S 120.13 Menacing in the first degree.
A person is guilty of menacing in the first degree when he or she
commits the crime of menacing in the second degree and has been
previously convicted of the crime of menacing in the second degree
within the preceding ten years.
Menacing in the first degree is a class E felony.
S 120.14 Menacing in the second degree.
A person is guilty of menacing in the second degree when:
1. He or she intentionally places or attempts to place another person
in reasonable fear of physical injury, serious physical injury or death
by displaying a deadly weapon, dangerous instrument or what appears to
be a pistol, revolver, rifle, shotgun, machine gun or other firearm; or
2. He or she repeatedly follows a person or engages in a course of
conduct or repeatedly commits acts over a period of time intentionally
placing or attempting to place another person in reasonable fear of
physical injury, serious physical injury or death; or
3. He or she commits the crime of menacing in the third degree in
violation of that part of a duly served order of protection, or such
order which the defendant has actual knowledge of because he or she was
present in court when such order was issued, pursuant to article eight
of the family court act, section 530.12 of the criminal procedure law,
or an order of protection issued by a court of competent jurisdiction in
another state, territorial or tribal jurisdiction, which directed the
respondent or defendant to stay away from the person or persons on whose
behalf the order was issued.
Menacing in the second degree is a class A misdemeanor.
S 120.15 Menacing in the third degree.
A person is guilty of menacing in the third degree when, by physical
menace, he or she intentionally places or attempts to place another
person in fear of death, imminent serious physical injury or physical
injury.
Menacing in the third degree is a class B misdemeanor.