I don't think 'reverse racism is a thing' societally, because the point is it's all about power balance. An individual person of colour, or a group of people of colour, can be prejudiced against white people, but it isn't racism as their dislike/hatred basically.... has not impact on white people as a whole.
Such prejudice might have impact on an individual or small group in a very specific context - say, if there were a business with only two white people in it and everyone else treated them very badly, I expect those two employees would have a legal case for racial discrimination, as they were discriminated against because of their race.
But for society as a whole there is a reason Kumar's comment is acceptable, but not the other way around. His comment does not cause problems for white people in the way every racist comment, or even unintionally racist comments/action impacts on all PoC given that power is so centred on white people.
I mean, as a hypothetical, say you have a big group of PoC who really hate white people and go around saying they're inferior, they smell, they stupid and shouldn't be in charge. It could have a lot of members everywhere, but it wouldn't actually have any impact on the dominance of white power. But every white racist is capable of increasing negative impacts for PoC as a whole group.