Given that this particular undefined behavior usually causes crashes in practice, I expect the author is talking about casting away the const but not actually writing to the pointer. Which is legal.
He never said he needs to cast away const to do what he is attempting to do, he just said that he wants to cast away const to reduce clutter, even though the program would have the same semantics as if he kept the const.
If only there were a way to indicate the function argument isn't mutated. </s>
My spidey senses tingle whenever I see const-ness cast away because it almost always means something is wrong. Either a function is missing a qualifier on an argument, or something very unsafe is happening. Why force callers to cast away const-ness in hopes that everything will be fine when you can just write the correct function signature.
Given that this particular undefined behavior usually causes crashes in practice, I expect the author is talking about casting away the const but not actually writing to the pointer. Which is legal.