Should we return the greeting of Al-Khidr when he utters it?

Scholars have differed regarding the life of Al-Khidr, with the preponderant opinion being that he is deceased. As for greeting him with "peace be upon him" when he is mentioned, like the rest of the prophets, scholars have differed concerning his prophethood, and the correct view is that he was a prophet. Therefore, it is appropriate for us to invoke blessings upon him by saying, "Al-Khidr, peace be upon him."