Never seen a Coquillage make a "normal" trap, nor have I ever heard about it "reverting" to normalcy. And I didn't know that it originated as a TC mutation. The trait is quite genetic, as it readily produces offspring via seed that look very much like the parent plant.
Coquillage is one of my favorite flytraps. Very vigorous, flowers often and strongly, and produces a lot of seed. I wouldn't hesitate to recommend it to someone if they enjoy the way it looks. They won't be disappointed. With a market full of different named flytraps, Coquillage is definitely one I'd recommend for anyone. And I have grown nearly all of the named flytraps to this point!