lock them up

The gemara (Sanhedrin 17) quotes three opinions as to what Eldad and Meided prophesized: 1) that Moshe would die and Yehoshua would lead the people into Eretz Yisrael; 2) that slav birds would come; 3) the future war of Gog and Magog.  The gemara then asks: b'shlama according to the view that they prophesized that Moshe would die, we understand Yehoshua's reaction of "Adoni Moshe kila'eim," lock them up, but according to the other views of what their prophecy was, why did Yehoshua get so agitated?  The gemara answers that Yehoshua held that Eldad and Meided prophesizing in the presence of Moshe was a violation of moreh halacha b'fnei rabbo (see Meg 14b as well and post here) which disrespected Moshe.

Why did the gemara accept Yehoshua's harsh reaction to the prophecy that Moshe would die as justifiable even without the sevara of it being moreh halacha b'fnei rabbo?  If it is a true prophecy, then no matter how uncomfortable the message, Eldad and Meided would have to transmit it and Moshe would have to accept it.  Plenty of nevi'im unfortunately for us were given the job of delivering unpleasant messages to Klal Yisrael.  Why did Yehoshua demand that they be silenced? 

The gemara (Shabbos 30) writes that David haMelech knew that he would die on Shabbos, so every Shabbos he would immerse himself completely in learning so that the malach ha'maves would not be able to overcome him.  R' Zev Hoberman z"l in his sefer Ayeles haShachar writes that if the torah of David could keep the malach ha'maves at bay, kal v'chomer the torah of Moshe Rabeinu.  This is what bothered Yehoshua.  How could the prophecy of Eldad and Meidad be true?  Moshe meis?  Moshe Rabeinu is kulo Torah, his entire being was dedicated to giving over Torah!  Eldad and Meided must be silenced because there is no way their prophecy could be true.

The Maharal In Gevuros Hashem writes that the Torah's explanation for Moshe's name, "ki min ha'mayin mishi'sihu," is not just a reference to the isolated event of his being drawn from the water by Pharoah's daughter.  Water represents chomer, unformed matter.  Water has no shape of its own; it will take on the shape of whatever container you put it in.  The opposite is pure tzurah, something that transcends the chaos of physical matter.  Moshe's name reflects the essence of who he is -- "min ha'mayin mishi'sihu," completely removed from chomer.  Moshe is pure tzurah, pure spiritual essence.  

Rav Hoberman uses this approach to defend the Shach (Y.D. 242), who paskens that one is not allowed to call one's rebbe by name in their presence even if preceded by an honorific, e.g. Rabbi Ploni.  How then could Yehoshua uses Moshe Rabeinu's name?  When Yehoshua used Moshe's name he was not using it as an appellation for Moshe the person, like Joe or Bob or Ploni, but rather he was using it as a description of who Moshe was, someone completely divorced from chomer, like the Maharal explains.  Death is something that can effect only chomer, the physical world.  But Adoni **Moshe** -- ki min ha'mayin mishi'sihu -- pure tzurah, is surely immune to such a fate.