BTW, one very strong rayah the pro-techeiles camp has is that the fact that the gemara goes to great lengths to teach us how to differentiate between the plant dye and the real techeiles, but never warns us of another fraudulent animal dye means that there is no other such animal. Otherwise, why did the gemara not give simanim as to how to differentiate the two animal dyes, the fraudulent and the real techeiles, just as it gave simanim on how to differentiate the plant and animal dyes? The pro-techeiles camp therefore says that we must have the real thing, since there is only one possible animal that produces a blue dye.
At any rate, because of the kashyas listed in my previous post by the anti-techeiles group, Rav Perr is opposed to the use of the current mollusk dye because he feels it will then take on the status of a mesorah, when it is still a safek, and in the future, people may come to rely on the mesorah, although it hasn’t be proven 100%.
I highly recommed getting a copy of the OU sourcebook. The topic is fascinating.