Surely this thing is known

And he said, Who made thee a prince and a judge over us? intendest thou to kill me, as thou killedst the Egyptian? And Moses feared, and said, Surely this thing is known.
Exodus 2:14

Moses intervened to settle conflicts between the Hebrews since he saw them as his people. He committed murder in the process and the people he tried to help rejected his authority. Moses had to face the consequence of his actions. He became a fugitive.

There is consequence for every action and there's no excuse. Moses learnt his lesson. God was merciful to him when Moses realised that he could not deliver his people from slavery all by himself. God chose him at the appointed time to lead his people out of Egypt.