Fat Steve
The poodle bites, the poodle chews it.
Anyone takes something out of your hands in an effort to intimidate you? That's assault, a crime. You take something out of my hands in a store, I will not so politely remind you that you committed assault. Continue to make an issue of it and you can explain to the police why you think you are allowed to do that.
This was a bass. Sitting on the sales floor. With a price tag on it, not a sold sign. Clearance and used items are first to pay wins.
The "dbag" committed no crime here. Total jackass, yeah, but not a criminal. If OP took it out of his hands after he picked it up off the floor, that could technically be assault depending on words exchanged and other factors. At that point, it is not paid for, the store owns it, the store decides who gets it. Let them handle it. NEVER physically intervene, guy could be a psycho waiting in the parking lot for you.
Take the high road and walk away, not a hard thing to do.
Oh GAWD! Assault? Oy vey, vhut is this world coming to? Bunch of prissy little special and unique snowflakes.

what did that poor bass do to deserve this?