It's not about "won't murder me" it's about "won't murder their own tribe". Humans are very tribal creatures, and we have all sorts of built-in societal taboos about betraying our tribe.

We also have taboos against betraying/murdering/whatever people of other tribes, but those taboos are much weaker and get relaxed sometimes (eg. in war). My point is, it takes significantly more anti-social (ie. evil) behavior to betray your own tribe, in the deepest way possible, than it does to do horrible things to other tribes.

This is just as much true for Russians murdering Ukranians as Ukranians murdering Russians, or any other conflict group: almost all Russians would consider a Russian who helps kill Russians to be more evil than a Russian who kills Ukranians (and vice versa).