It is difficult to understand why Moshe should have been punished for exhibiting mesiras nefesh for Klal Yisrael. In addition, why was Tetzaveh specifically chosen as the place to delete his name?

When Hashem first approached Moshe at the Burning Bush, Moshe questioned his worthiness to lead Klal Yisrael out of Egypt. Even after Hashem had answered all his doubts, Moshe still replied, "Send this mission with the one you usually send" (Shemos 4:13). Here Moshe revealed the real reason behind his unwillingness to accept this mission.He was afraid of slighting his older brother Aharon, who had suffered together with Bnei Yisrael and had been, until then, G-d's emissary to them. Moshe was afraid that Aharon would be hurt if his younger brother was chosen over him.

Hashem responded in anger. According to R' Yossi (Zevachim 102a)+--- Moshe was actually punished for his reticence. He had been destined to be the progenitor of the line of Kohanim and Aharon an ordinary Levi. Now this designation was reversed.

On the surface, it seems incongruous that Moshe should have been punished so severely for refusing the mission out of sensitivity to his brother's feelings. To appreciate the subtle deficiency that Hashem found in Moshe, we must first discuss two divergent approaches to avodas Hashem.

The first approach is reflected in the words of Chazal, "Our will is to do your will." This implies that our service to Hashem starts with our subjective will. We wish to do that which is good for us, and we conclude that fulfilling the will of Hashem is what is best for us in theis world and the next.1 The second approach is reflected in the words of Chazal in Pirkei Avos (2:4) "Make His will as your own." In this approach, Hashem's will is the starting point and one subjugates his own personal desire to Hashem's will, disregarding any subjective preferences.

The latter approach is reserved for special individuals - lovers of Hashem (see Ramban to Shemos 20:6) Ahava is serving Hashem with no thought of personal reward; yirah is with one's own personal reward in mind.

We can better understand the following exchange between Moshe and Hashem. After the first two of the Ten Commandments were given, the people approached Moshe and said they were afraid that if they continued to hear Hashem speak directly, their neshamos would leave their bodies forever. They begged Moshe to be an intermediary between themselves and Hashem.

Moshe was devastated that the people did not want to approach Hashem directly out of love and would rather hear the Torah indirectly. But Hashem responded to Moshe's disappointment that the people had spoken well: this great fear of His and desire to observe all His mitzvos should remain with them and their children forever.

Moshe was agitated that the people considered their own welfare and were not selflessly dedicated to relating tho Hashem directly, even at the possible cost of their lives. That is the level of selfless love. Their fear of dying while listening to Hashem's words reflected that lack of complete selflessness. Hashem responded, halevai that they should remain on the level of Fear of G-d, where service to Hashem is measured by the subjective understanding that doing Hashem's will is the best course for a person. This level is not yet that of selfless love, but it is nevertheless an admirable one for the masses.

Rebbe Zusya was once asked if he would be happy to change places with Avraham Avinu. He replied: "What would Hashem gain - there would be still one Avraham Avinu and one Reb Zusya?" That is the attitude of ahavas Hashem in which one's personal reward is absolutely irrelevant.

Chazal tell us that one who suspects another wrongly is smitten in his own body (Sabbos 97a) If there are not grounds to suspect another, then the suspicion reflects the one who is suspicious. He knows that if he were in a similar position himself, he probably would have acted as he suspects his friend of acting. Therefore, his suspicion is based on a personal blemish, and this is the personal impairment which Chazal refer to as being smitten bodily.

Moshe's suspicion that Aharon would feel slighted was groundless. Hashem told Moshe that Aharon would have nothing but joy in his heart upon hearing that Moshe had been chosen. Therefore the basis for Moshe's susbicion must have been within himself. And it was this slight blemish that Hashem responded to by punishing Moshe.

A kohen becomes G-d's agent and representative, and therefore must be a selfless servant, totally negating his own self. If Moshe could not free himself of the self-concern he projected onto Aharon, he was found unfit to be the kohen. Aharon's selflessness was beyond question - it made no difference to him who the redeemer was as long as Hashem's mission was fulfilled - and he was thereore found fit to be the Kohen Gadol.