All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It is permissible for a man to use whitening creams if it does not cause any harm. A man may beautify himself and apply what is Islamically permissible to his skin, but the problem here is that doing so for the purpose of proposing to a girl is not permissible because it is cheating and deceiving the girl to whom he proposes. Indeed, Abu Hurayrah narrated that the Prophet said: “Whoever cheats is not one of us.” [Muslim]
What you mentioned that the superiority or excellence is achieved through piety is correct as per the authentic Hadeeth to which you referred, but your friend being determined to use that cream does not necessarily mean that he has an inferiority complex, so your statement in this regard may not be appropriate.
Allaah Knows best.