Gollum, snrk.
Sauron was never a giant eye, but it's true that he couldn't maintain physical form at the Siege because it had been sliced and diced by our heroes.
One point: The passage reads "Then Sauron was for that time vanquished" after a sentence including the terms
"Sauron also was thrown down" and "Isildur cut the Ruling-ring", so there is no basis in saying that this "vanquished" line supports one or t'other.
the phantom makes a good point (*gasp*) when he says that maybe there was no final blow before Sauron decided to leave his body.
In The Council, Elrond tells that "Sauron himself was overthrown, and Isildur cut the Ring from his hand..." This seems like good support for not choosing Isildur as the one who delivered the 'final' blow, which I read as that blow which crippled Sauron's body.
Fordim, you should have made it a choice between Isildur and Elendil/Gilgalad. Once more you have incurred pettiness at the structure of your polls. You'd think you would have it sorted by now.