Between a human and a beast, he believes that if he can kill one of them, he should be able to kill both of them.
He also believes that if there is something wrong with killing one of them because of their race, then there should be something wrong with killing both of them.
It took 12 years to learn that lesson. Thanks to them, he doesn't care about race anymore. He only cares about strength.
If he were on Earth, this mentality would be wrong. But he is no longer on Earth. He is in Ethera.
In Ethera, this is the mentality he needs to survive. It is the mentality that everyone else has. As they say, when in Rome, do as the Romans do.
On Earth, he can at least call the police if someone is trying to kill him. On Earth, a murderer will also be jailed or killed as punishment for their crime.