Aron and Chur

Chur was a great man. He did not hesitate to sacrifice his life to prevent the Jews from creating a golden calf. Yet the Torah does not mention him in the story at all. Why?

I have an idea that may or may not be correct; here it is:

At that point in Jewish history, the Jewish people were not yet commanded to sacrifice their lives to avoid idol worship (The commandment is found in Leviticus 22 34). Perhaps the reason we don't emphasize the greatness of Chur's commitment, is that one may not sacrifice their live without an explicit commandment from Hashem.

If this answer is correct, then Aron would be completely exonerated. As it would be against the Torah for Aron to sacrifice his life to avoid making the golden calf.  

By omitting Chur’s sacrifice the Torah is conveying the importance of life, saying that one may not give up his life even for the noblest of causes, without the direct commandment by Hashem.

I find it interesting that we celebrate the Akeydah as the first act of martyrdom, although nobody died. This emphasizes that we celebrate the willingness to die, never death itself.