Did you notice? One of the last refuges available to Techeiles dissidents (defeated by all the central proofs) is to say we don’t know what exact shade of blue is required. So, even conceding the murex source of Techeiles is genuine, we still cannot use it until and unless an Amora with perfect eyesight returns from the dead and testifies to an unbroken tradition since Moshe Rabbenu (and then I presume they’ll find some new excuse).
Of course, there is zero reason to ever assume the exact shade even matters. The Biblical word “Techeiles” refers to a material (same as “Argaman”, not a hue on a spectrum at all (as also admitted by leading Techeiles opponent Rabbi Inbal). (I vaguely recall Levush HaAron does bother to provide some proof against the baseless idea anyway.)
And the source of this objection is the responsa volume falsely and with malice aforethought attributed to Rishonim, the “Besamim Rosh”…
So… they are worried about lacking a tradition because of something which not only lacks a firm tradition but is a Maskilic forgery specially designed to uproot Torah and mitzvos.
I find something ineffably poetic about that fact.