Sam2,
Unfortunately, I don’t have access to my notes (right now) from when I learned this sugya. Bli Neder, next time I am at home I wil look it up and direct you to the teshuvos.
R’Moshe holds that hand shaking is objectively “derech chiba” because the purpose of the handshake is to bring the two people closer (to create a bond in some fashion).
I should clarify that even according to R’Moshe improper thoughts from negiah that is not derech chiba are asur under Lo Sasuru (but they are not yehoraig v’al yaavor because Lo Sasuru is not abazrai d’gilui arayos).