It's the E series lights that removing the clip leaves a gap for the bezel o-ring to squeeze into, and become misshapen-hence compromising the seal formed by that o-ring.
Removing the clip should have no effect on the water resistance of the C2, whose bezel seal is made by an o-ring well forward of the clip/base of the bezel.
Removing the clip should have no effect on the water resistance of the C2, whose bezel seal is made by an o-ring well forward of the clip/base of the bezel.