You can never justify genocide because killing innocent people was wrong no matter how you spin it (even though some dictators tried).
Everyone Alonso harassed, stole from, killed was a drug peddler/user. He harassed Snoop and put him in a wheelchair because he knew he was going to be helpful later on. He stole from the Sandman to buy the warrant to kill Roger but he was just another drug pusher. He killed Roger, who turned out to be one of the biggest kingpins in LA (for the money) but he said it was justified because he poisoned the streets with those drugs. So in turn rather he was bullshytting Jake and decided to finally take him out because there was a bounty on his head, he killed two birds with one stone.