Согласен
Кроме того, Исильдур не "таинственно исчез" - его останки нашел Саруман.
И первое упоминание о назгул - это 2251 год ВЭ. Тысяча лет до рождения Исильдура, однако.
А поподробнее - в UT, "The Disaster of the Gladden Fields". Там сказано, что после воцарения Короля Элессара, он вошёл в Ортханк и исследовал его. Там он нашёл две вещи: первой был "...small case of gold, attached to a fine chain; it was empty, and bore no letter or token, but beyond all doubt it had once borne the Ring about Isildur's neck,"- а второй - первый Элендилмир (не тот, что носили короли Арнора): "Next to it lay a treasure without price, long mourned as lost for ever: the Elendilmir itself, the white star of Elvish crystal upon a fillet of mithril that had descended from Silmarien to Elendil, and had been taken by him as the token of royalty in the North Kingdom. Every king and the chieftains that followed them in Arnor had borne the Elendilmir down even to Elessar himself; but though it was a jewel of great beauty, made by Elven-smiths in Imladris for Valandil Isildur's son, it had not the ancientry nor potency of the one that had been lost when Isildur fled into the dark and came back no more. "