Alma 55:19

But behold this was not the desire of Moroni. He did not delight in murder or bloodshed; but he delighted in the saving of his people from destruction; and for this cause he might not bring upon him injustice, he would not fall upon the Lamanites and destroy them in their drunkennes.

But Moroni did not want to do that. He did not like murder or killing. He wanted to save his people from being destroyed. For this reason, he would not do something wrong. He would not attack the Lamanites and kill them while they were drunk.

But that wasn’t what Moroni wanted. He took no pleasure in murder or bloodshed. What he cared about was saving his people from destruction. To avoid bringing injustice on himself, he refused to slaughter the Lamanites in their drunkenness.