Why did you automatically bring "ethics" into this discussion? The person you replied to was probably using the word 'should' in reference to some other objective.
To me that seems like a non-sequiter.
There is no reason to suspect that the optimization (with respect to whatever objective you desire, e.g. total happiness) of a large, complex, chaotic, system (such as a society) can be best achieved by using 'ethical correctness' as the only criterion for decision making.
At least, that's my opinion. I hope that doesn't make me an indecent human being.