“mik5: “Even if he knows with 100% certainty that shaking her hand will not lead him to have bad thoughts, it is still 100% assur to shake her hand”
That is actually not true. There is a B’feirush Gemara against that.”
If derech chiba WITHOUT being neheneh b’kiruv basar was trully Yehareig V’al Yaavor, as what many people are claiming, then the gem would say one must sooner give his life up to shake her hand even when he is not being neheneh, which it does not. Thats my point.