Neville, again this is not a sugya that was addressed head-on by the Gedolei Haposkim. The crux of Rav Elyashiv’s teshuva relates to the general question of נאמנות החוקרים, not the powerful evidence raised by talmidei chachamim today.
Importantly, Rav Elyashiv never rules out this is Techeiles. On נגנז he cites ישועות מלכו, who himself doesn’t consider his interpretation of נגנז conclusive (Chacham’s comment above and ישועות מלבו סי’ ג).
Rav Gershon Meltzer, when discussing Techeiles in his sefer Living Halacha on Hilchos Tzitzis, cites Rav Moshe Halbershtam who says someone who didn’t go through a Sugya doesn’t have a din of חכם שהורה.