Nobody’s perfect, but sometimes one side really is right and another is wrong.
The civil rights reformers were not perfect, but they were right that racial oppression was wrong. In that setting, whites who wanted to stand for justice needed to join the “black side.” The British, French and Americans were far from perfect, but Hitler’s genocidal activity was pure evil. Fighting for justice in such circumstances could be standing for the “Jewish side.” When North Korea tortures and imprisons detractors, or ISIS or other religious vigilantes in Central or South Asia kill Christians or other religious minorities, these acts are evil. In our narrative, God was clearly on the side of the slaves. They were far from perfect, but they were unjustly oppressed—and they were God’s people.
Probably no one would have taken note when Moses went to visit his fellow Israelites; probably no one would by spying on this person of status despite his ethnic affiliation. Moses witnesses his people’s difficult “burdens” (Exodus 2:11), a term describing their work as an enslaved people (in the OT found only in Exodus; see also 1:11; 5:4-5), burdens from which the Lord their God would ultimately deliver them (Exodus 6:6-7).
But seeing an Egyptian “striking” a Hebrew, he “struck” the Egyptian (the same Hebrew term, often applied to killing). Moses intended the lethal outcome of his blow; he first made sure that no one was looking before he killed the Egyptian (Exodus 2:12). The law of Moses later required the penalty of death for deliberately striking someone lethally (Exodus 21:12), but Moses may have been saving the life of the Israelite being beaten. Certainly later Jewish interpreters and biblical voices understood Moses as acting for justice (cf. Acts 7:24-25). Moses identified with his enslaved people more than with his own privilege (cf. Hebrews 11:24-26).
Moses hid the corpse in the sand (Exodus 2:12). (A contrast with Moses’s mother positively hiding him is possible but unlikely, since the narrator employs a different Hebrew term.) Moses did not expect to get caught, and trusted that his fellow Israelites would appreciate his action and not circulate it. But even if the Hebrew he rescued appreciated the action and was the only witness, questions about his own escape from beating might well lead to him recounting the story, and word about the action of this privileged Hebrew would quickly spread (see Exodus 2:14).
Although Moses’s action may prefigure his future role as deliverer, the difference between his failure as a small-scale deliverer here and his future success as an agent of God’s deliverance is clear. It’s not enough even to be right about our calling or destiny: we need to depend on the Lord to get us there. It’s important to stand for justice, but it’s ultimately the Lord who grants success. It is difficult to even quantify the vast chasm between Moses’s act of avenging and hopefully rescuing one Hebrew and the plagues that would later force Pharaoh to release Israel. It is the difference between the arm of flesh and the arm of the Lord.