It would negate Isildur's free will because he would be physically forced to destroy the Ring, i.e., against his will.
But, like I said in my last paragraph, the point is moot if, as I think, no one could voluntarily destroy the One Ring of Power.
If it came down to it, I'm sure Cirdan and Elrond together probably could have forced Isildur into the Crack. But I don't believe it ever could have gotten that far.
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"If you're referring to the incident with the dragon, I was barely involved. All I did was give your uncle a little nudge out of the door."
THE HOBBIT - IT'S COMING
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