mw – yes, possibly. but i am sure that those who advocate for not being nice are doing so believing they are right, and they are the more vocal and visible ones and set a very bad example for halachik Judaism.
Like the story of Rabbi Silver in the DP camps. when a man gave up religion because he saw someone charging a days ration of bread for the use of his siddur. Rabbi Silver told him he should have looked at the line of people volunteering to do so instead. It is human nature to see the badly behaved and think them representative of the whole. which is wrong. But by the same token, people representing the learned *should* know better, shouldn’t they? Even those who hate us are expecting more from our behavior.
You are assuming the person in the presents-at-the-table scenario isn’t fully believing that this extra shtuch to the non-Jew is part of fulfilling the mitzvah. And that is the sole reason that when you call him on it, he believes you are denying the truth of the mitzvah itself.