First, listen to the shiur here (only the first 25 minutes).
As Rabbi Kallus says himself, he has a detailed shiur against Techeiles elsewhere. And he notes (I think) Rabbi Rosenberg’s rebuttal we posted here. This one is just his general argument.
(Speaking of “kallus”, I only listened to this once (see B.B. 98b), but this is a blog… And I don’t recall his more detailed arguments right now.)
Two short points from Hyehudi Editor in response (based partially on Rabbi Y. Brand, as is usual):
One, it’s not about so-called “Simanim” for so-called “Techeiles”, as the rabbi continually misframes the question. The Tosefta says: “תכלת אין כשרה אלא מן החלזון, שלא מן החלזון פסולה”. No one disputes the kindergarten-level marine science that this is a type of “chilazon” (and, by the way, the Radzin specimen is not, which is why it doesn’t belong in the debate). So, for example, the seeming contradiction about it coming up every 70 years, or certain disputes among Rishonim about the details, and so on, hardly matter. Case nearly closed.
Two, those who wear Techeiles are following the rules of deciding halacha (כללי הפסק), no different than the rest of the Torah. And, yes, Mashiach can cast doubt on this or any other pesak. Mashiach can “even” say our Esrog Mesorah went awry (Pop Quiz: Did the Chazon Ish have a mesorah for his esrog, especially as regards מורכב?). But we would still have been 100% retroactively justified in going with present human knowledge, in this as in any other new topic. And turkey-eating opponents of Techeiles with their ad hoc meta-halacha would still be absolutely unjustified. (The rabbi sometimes says “Eliyahu” and sometimes “Mashiach”, by the way. I truly don’t know how he understands the gemara of אם יבא אליהו ויאמר חולצין במנעל, etc.)
(By the way, and this may be unfair since Rabbi Kalllus’ words here aren’t “סוגיא בדוכתה”, but I don’t get the sense the rabbi even understands what “mesorah” in the specialized (Chagav, Zebu, etc.) sense means, namely, the assurance we are applying Chazal\Torah simanim (which theoretically should be enough for any child in the middle of a desert) correctly in a given case. In more words, no one learns from the rabbi what mar’eh is tahor (a simple reality in most cases), but only gradually acquires the beki’us of any adult female human in lining up his sights with the corresponding Shulchan Aruch, אכמ”ל).
Rabbi Kallus can say what he likes, but murex is truly not even a safek, so we can produce bigdei kehuna today with shatnez for practical use, too.
P.S., Rabbi Kallus is highly doubtful (or at least overconfident) in his many extras and asides (which, unless the rest of this rabbi’s Torah recall is this rotten, proves how unseriously (in the best case) he and his ilk take this sugya!): “All” the “Gedolim“, what the Arizal actually says, the absolute obligation or Issur Aseh בזמן דאיכא תכלת, Rabbi Kanievsky’s final view, Rabbi Elyashiv’s juvenile “מין כנף” humor, Brisker belief, the baseless “tzad” one needs mesorah here at all — Lekula! (and this has nothing to do with the steelmanned version of the Beis Halevi). Not to mention, one can define what we know as approximating mesorah, anyway, e.g., the minuscule number of fast, natural dyes in existence, the same dye being common in the time of Chazal (and no mention of fakes except קלא אילן), the Achronim we follow, the millions of shells exactly where Chazal said Techeiles was dyed; כאן נמצא כאן היה, etc.
Let it be clear I intend no disrespect for this rabbi who, I am informed, is a Torah scholar, no matter how well he hides the fact. I believe his tone (forgetful of אהוב את השמא ושנא את המה בכך) amply justifies my own.
