לָכֵ֖ן אֱמֹ֑ר - HaKsav v'HaKabbalah on responding to criticism; a proof meant for us

1) Our parsha opens with Hashem declaring that Pinchas would be rewarded:  לָכֵ֖ן אֱמֹ֑ר הִנְנִ֨י נֹתֵ֥ן ל֛וֹ אֶת־בְּרִיתִ֖י שָׁלֽוֹם  Netziv writes מלבד שיהא כן, יודיע לו שיהא כן. והוא חיבה יתירה.  Meaning, we see from the pasuk not only that Pinchas was rewarded, but לָכֵ֖ן אֱמֹ֑ר, but also that his reward was announced, which shows Hashem's special love.  Meshech Chochma in many places quotes a yesod from the Rambam in the into to Peirush haMishnayos that a nevuah that is just revealed privately to a navi can be changed and retracted, but a nevuah which the navi is told to declare can never be changed.  Therefore, Hashem not only showed Moshe was Pinchas' reward was, but he told Moshe to articulate that promise so that it would never be subject to retraction.   

The reward given to Pinchas stands in contrast to the reaction of the shevatim to his actions.  Rashi writes that the shevatim criticized Pinchas for killing Zimri, saying that it was not right for the gransdon of an oveid avodah zarah to kill the nasi of a sheiveit.  HaKsav v'haKabbalah interprets the word אֱמֹ֑ר here along the lines of the pasuk  וה' האמירך היום להיות לו לעם סגלה כאשר דבר־לך ולשמר כל־מצותיו (Devarim 26:18)  Ibn Ezra there translates  מלשון גדוּלה, like בְּרֹ֣אשׁ אָמִ֑יר (Yishayahu 17:6), meaning, "the uppermost branch."  Before even talking about the reward for what he did, Hashem told Moshe that if Pinchas is being criticized, לָכֵ֖ן אֱמֹ֑ר, you have to pick him up, you have to give him immediate affirmation.  What a great lesson in how to react and respond when you see someone being put down for nothing.

2) Rashi writes that because the nations cast doubt on the purity of the families of Bn"Y, therefore, there is a letter hey before each family name and a letter yud at the end in our parsha because Hashem wanted to show that his name was connected with each family, a testimony to their purity:  

 לפי שהיו האומות מונין אותן: מה אילו מתייחסין על שבטיהם, סבורים הם שלא שלטו המצריים באמותיהם, אם בגופן היו מושלין קל וחומר בנשותיהם, לפיכך הטיל הקב״ה שמו עליהם, ה״י מצד זה ויו״ד מצד זה, לומר: מעיד אני עליהם שהם בני אבותיהם.

Are the nations of the world who had this taanah going to open our parsha and start reading and see this connection to the shem Hashem?  Do you really think this will convince them that they are wrong?

R' Chaim Elazari in his Nesivei Chaim answers that the proof is not meant for them -- it's meant for us.

When you live in a society surrounded by the umos ha'olam and you hear them talking, sometimes a little of what they say seeps in.  Witness how many poor misguided Jews sadly have been brainwashed by what they hear on college campuses, mainstream media, the internet, and the Democrat party, and have come to think that the poor Palestinians are victims of Israel's aggression, or have come to think that supporting some alphabet soup of LGBT+whatever else rights is a value that we can subscribe to.  The parsha is meant for us, to reaffirm what we know the truth to be against the tide of lies that come from elsewhere.  (I assume he would explain the first Rashi in Braishis in a similar way.)