ה. וַיְהִי בִישֻׁרוּן מֶלֶךְ בְּהִתְאַסֵּף רָאשֵׁי עָם יַחַד שִׁבְטֵי יִשְׂרָאֵל
5. And He was King in Jeshurun, whenever the sum total of the people were gathered, and the tribes of Israel were together (Devarim 33:5)
This Pasuk teaches us that Moshe was appointed King of Yisroel, ‘בְּהִתְאַסֵּף רָאשֵׁי עָם’, after the Torah was given on Har Sinai.
In the Parsha this week, Yisro comes to Klal Yisroel in order to convert, slaughters a certain offering to Hashem, and makes a lavish feast. Rashi (18:12) says that Moshe didn’t sit and eat during the feast, rather he stood and served everyone.
The Meshech Chachmah asks, how was Moshe able to be forgo his honor by serving the guests? A Rav or Nassi can forgo their honor, but a King can never forgo their honor (see Kedushin 32b)? He answers that there is a Machlokes Tannaim in regards to when Yisro came to Klal Yisroel. One says before Matan Torah and one says after (could even be after the Hashkamas Hamishkan). If Yisro came before Matan Torah then we don’t even have a question because Moshe was only King after Matan Torah. But, if we say Yisro came after Matan Torah then our question stands and how was Moshe able to be Mochel his kovod? Thus the Meshech Chachmah has to answer that according to the one who holds Yisro came after Matan Torah, then the aforementioned Rashi doesn’t exist, that Moshe never served during the meal and he really sat and enjoyed like a King.
The Meam Loez gives a different answer. Gem. Sota 31b says that Agripas Hamelech used to read the Torah on Hakel standing up in the Bais Hamikdosh. Everyone knows that the King is allowed to sit, but Agripas would still stand. The Chachamim said that Agripas was absolutely right and righteous for standing in the Bais Hamikdosh. The Gemerah asks, but Agripas was a King, so how did he forgo his honor? The Gemarah answers that a Mitzvah is different. Meaning that since a Mitzvah was being done (Hakel) Agripas was able to forgo his honor for the sake of doing a mitzvah. Tosofos there asks that we know a King can’t be Mochel his Kovod from a Gem. in Kedushin 32b. There it retells the story how Rav Gamliel (a Nassi) served his guests at a certain Seudas Mitzvah. The Gemarah asks, how can he be Mochel? In which it answers a Nassi can be Mochel his Kovod and that only a King cannot be Mochel. There the Gemarah was dealing with serving his guests at a seudas mitzvah and the Gemarah says that a Nassi can be Mochel, but a King, even by a Seudas Mitzvah, isn’t allowed to be Mochel. So what is the Gemarah’s answer that a King can be Mochel his Kovod if he is doing a mitzvah if the Gemarah in Kiddushin clearly doesn’t hold that way? Tosofos answers that to accomplish a regular mitzvah the King wouldn’t be able to be Mochel his Kovod, whereas a mitzvah which involves the Shechina to come a King could be mochel. Therefore Agripas was able to stand up in the Bais Hamikdosh for the Shechina was there.
The very next Rashi in the aforementioned pasuk 18:12 says that when you eat at a meal with talmidei chachamim its as if you benefited from the ”Ziv Hashchina” (Maharsha says for Torah will be discussed at such a meal. For another reason see Gur Aryeh). Now we have a pashut answer. The meal Moshe was serving was a meal hosting many Talmidei Chachamim. Thus the Shechina was at the meal, (as Rashi pointed out) and even if we were to say that Yisro came after Matan Torah, Moshe could still be Mochel his Kovod for the sake of the Mitzvah which involves the Shechina. (Only question is, why wasn’t the Shechina by the meal of Rav Gamliel? There it was a Seudas Mitzvah with Talmidei Chachamim and yet only a Nasi was able to be Mochel, but not a King? A bit of a Tzarich Iyun. This question could be why the Meshech Chachmah didn’t want to answer like the Meam Loez.)