How was Moshe protected by the sand in Egypt?

Question

Moshe does not enact the third plague. Rashi explains that,

לֹא הָיָה הֶעָפָר כְּדַאי לִלְקוֹת עַ"יְ מֹשֶׁה, לְפִי שֶׁהֵגֵן עָלָיו כְּשֶׁהָרַג אֶת הַמִּצְרִי וַיִּטְמְנֵהוּ בַּחוֹל,

That the dirt protected Moshe when he killed the Egyptian and buried him in the sand.

This comes from Sh'mot Rabbah 10:7

אָמַר רַבִּי תַּנְחוּם אָמַר לוֹ הַקָּדוֹשׁ בָּרוּךְ הוּא לְמשֶׁה עָפָר שֶׁהֵגֵן עָלֶיךָ כְּשֶׁהָרַגְתָּ אֶת הַמִּצְרִי אֵינוֹ דִין שֶׁיִּלְקֶה עַל יָדֶךָ

My question is -- in what way did the sand actually protect Moshe? While, yes, the body was buried, how does this protect Moshe? He had already been spotted and because of the comments of the other Hebrew men, he was in trouble and had to run away, regardless of the sand. What, exactly, did the sand do to protect him that it deserved such consideration?

Answer 1

This is similar to Rashi earlier, that Moshe couldn't hit the sea either since it had protected him as a baby:

לפי שהגין היאור על משה כשנשלך לתוכו, לפיכך לא לקה על ידו לא בדם ולא בצפרדעים, ולקה על ידי אהרן:

How did the water protect Moshe? It seems as if, even though these protections seem to just be aspects of nature doing what nature does, still Moshe had to be thankful for these two elements and what they did for him in his past.

As you point out, in the case of the sand, it didn't work since others brought the matter to light, but that doesn't negate the contribution of the sand. And perhaps this shows the lengths one needs to go to to be thankful, even for attempted helpfulness.

Answer 2

When Moshe killed the Egyptian, he buried the body in the sand; and the evidence of the deed remained hidden. The sand did its "job". End of story.

The fact that tale-bearers informed on Moshe, is considered a new issue, and does not in any way diminish the benefit of the sand.