>racism can only be perpetrated by the people who control the power structure
There's not one dictionary in existence that even mentions the "power structure" in the definition of racism. Even if that definition is someday added, that won't obsolete the current definition of racism which will still exist.
So why won't this "minorities can't be racist towards whites" meme die?
Because they want to be able to harass us. There are two ways to justify harassment:
1) dehumanize the victim
2) delegitimize the attack
If they do one or both of those things, they don't feel remorse when they hurt others.