i thought we went through this. just to throw a few at the dartboard kinda out of order: Malbin pnei chaveiro (deoraisa on jews, so if girl is a jew and gets embarassed bc u refuse to shake her hand for some strange excuse that sounds hard to believe, its there; presumably also applicable to goyim on some level at the very least); darkei shalom (need to bend our rules all the time in many varian halachos to keep peace with goyim so we dont grow their animosity and lead to danger, and even in us this can have effects, peeps will vote against religious rules (shechita/milah) or israel, putting peeps in danger); basic kavod habriyos is a factor in many halachos so respected people are permitted/excepted from certain rules; deracheha dachei noam (see several places in shas such as gitin 59 (where the gemara says darchei shalom is "deoraisah", and "the whole torah itself is for darchei shalom"), succa 32, yevamos 87); vasisa hatov vehayashar as explained as a positive command by Ramban/similar idea for kedoshim tehiyu, not to be a blind follower of halacha while being uncouth; pirkei avos (not really halachic but important) including r chanina ben dosa, if the spirit of the briyos are pleased by u, hashem is pleased by u. and im sure there is much more i dont have on the top of my head.
Let's take a different scenario for a second, that isn't so contentious, and I actually had yesterday. A co worker is an avid baker, and she offered me, all excited, a piece of something she had baked.
Her, all excited, in front of several others: Want to try a piece of this cake I made, it's really good, and I never made it before
Me: I'd love to, but I'm restricted to kosher. But it looks awesome!
Her, very deflated and confused: but cake doesn't have to be kosher?
Me: Actually it does
Her: well let me tell you what i put in, just...
and so on.
As gracefully as possible I extricated myself and hopefully no lingering hard feelings.
Now, I don't think anyone here would tell me that I should have had a bite, even though:
Malbin pnei chaveiro
darkei shalom
kavod habriyos
deracheah darkei noam
hedoshim tihyu
ruach habrios nocha heyemeno
etc.
And I could make the argument that there wasn't more than an issur derabannan, especially if there were no overtly non kosher ingredients. for gelatin you can be meikel. etc.
Now, on to another case. You're a lawyer in Santa Monica (Silicon Beach) and the office has a informal atmosphere. Your attractive paralegal says good morning by throwing her arms around you and giving you a peck on the cheek. In those circles that would be equivalent to a warm handshake in NY. Same as shaking hands? I think not, even though all the above 'clashes' apply.
Those considerations are considerations that were applied by Chazal in extenuating circumstances, and yes, occasionally even on a deroysa. but if you peruse centuries of responsa they weren't willy nilly applied to every scenario where the argument could be made.
Again, I'm not coming to knock anybody, or say anyone's doing the wrong thing. It's a very difficult call each time. But to say that one who is machmir is wrong is also not right.