The conditional :

if (abs(WorldSpaceReflectionVector.x) != M) WorldSpaceReflectionVector.x *= scale;

if often converted converted to a conditional mask on some GPU, like CndMsk(abs(WorldSpaceReflectionVector.x) != M, WorldSpaceReflectionVector.x * scale, WorldSpaceReflectionVector.x).

but yeah will be better to write it like abs(WorldSpaceReflectionVector.x) != M ? WorldSpaceReflectionVector.x * scale : WorldSpaceReflectionVector.x;

Which is not really different from what you are doing with equal/mix

res = CndMsk(abs(WorldSpaceReflectionVector.x) == M, 1, 0)

scale * v + res( v – scale * v) // lerp

Except lerp is two instruction by float