you dont say
You replied “You have that exactly backwards” when I pointed out then when you said “and making use of scientific inquiry to buttress an halachic argument.” you had it backwards
You also correctly pointed out:
“mesorah in halacha means a derech in p’sak — how to go about paskning”
Allow me to elaborate.
If yo uare looking for chilazon you woudl start with MEnachos 44a
חלזון זהו גופו דומה לים וברייתו דומה לדג ועולה אחד לשבעים שנה ובדמו צובעין תכלת לפיכך דמיו יקרים
Youd look for a fish wih the body comparable to the ocean that rises once in 70 years and whose blood is used to dye. you would never find the murex since it meets none of those criteria (though it is expensive 😉 )
now I grant if you find the murex through other means and are convinced it is techeiles the question that it isnt a fish isnt much of a question (perhaps all sea creatures are called “fish” not sure why the Gemara couldnt say sheretz hamayim, but ok not the biggest question) ditto for it not being the blood that is used.
However this isnt usually how halacha works.
For example take the argument over brain death those who accept it dont argue that it is death based on a scientific definition or modern research. The argument si that a patient who is brain dead is dead based on the Gemara in Yoma and/or mishna in Ohalaos. (This isnt the thread to debate brain death, I deliberately wrote the above in a (hopefully) non-controversial manner).
This just isnt the case with murex. the arguments are primarily scientific/academic in nature with the Gemaras treated as secondary (at best) and many Rishonim (like Rashi) ignored. This isnt how halachic pesak is generally determined