It is not that the publishing a photo/image of Baha'u'llah is forbidden to Bahá’ís; rather, the image of Bahá’u’lláh is very sacred to Bahá’ís and they do not wish for it to be viewed and engaged with in a casual manner.
It would be reassuring to me to learn that the Bahá’í Faith celebrates in the Bible the inspired words of God, venerate its many prophets, and loves Jesus, recognizes Him to be the Son of God who dedicated and sacrificed His life so we may live in grace and be quickened by the Spirit with eternal life in heavenly nearness to God.