Why manipulating $_POST?

Hi, really a question for your developers.
in file includes\classes\utils\Options.php, lines 138-141 in your code is:

private function setRequest( $key, $value ) {
	$key           = $this->get_key( $key );
	$_POST[ $key ] = $value;
}

Why and under what circumstances is this good practice to manipulate $_POST, even on GET request?
Second question, will you remove it?

Thank you!