That has been in the act for many years. As Monsieur Simard said, you cannot remove the Chief Electoral Officer without a resolution of both chambers, like any other officer of Parliament. One chamber alone cannot remove any officer of Parliament.
The reason they have given this power to the Senate in this case, even though the Senate is not involved in the appointment, is presumably for protection—to ensure that as Monsieur Simard said, the House by majority did not decide to remove a Chief Electoral Officer without some check from the Senate, which is presumably more objective in such matters.