Why do some blacks moan and whine about slavery?

[dazzn]

is it some inviolable "wrong" to point out that racism is wrong no matter the subject, and not when it suits one's agenda?

No, it just seems ironic for a moral nihilist to call anything "wrong" aside from, say, a wrong answer. Is there anything inherently illogical about hypocrisy? (It is possible that I am misunderstanding what you meant by this)
http://en.wikipedia.org/wiki/Tu_quoque

the appeal to hypocrisy, is a logical fallacy that attempts to discredit the opponent's position by asserting the opponent's failure to act consistently in accordance with that position; it attempts to show that a criticism or objection applies equally to the person making it. This dismisses someone's point of view based on criticism of the person's inconsistency, and not the position presented,[2] whereas a person's inconsistency should not discredit their position. Thus, it is a form of the ad hominem argument.[3] To clarify, although the person being attacked might indeed be acting inconsistently or hypocritically, this does not invalidate their argument.

So, if it isn't illogical, and there are no morals, then how can it be "wrong"?

In cases of intolerance, reverse hatred only increases tensions. it's not a mature or reasoned response. Hence, it makes the oppressed party no better than the oppressor.

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I agree with some of this because I'm white and when I was very very young I believed that white people seemed evil and all other races were peaceful until the white man came and corrupted them and enslaved them.
it was just after reading more into history I realized that it seemed to me that whoever has the upper hand usually fucks over the person who doesn't have the upper hand, and white people have generally had the upper hand in technology over the years.
But people of all races go to war and enslave each other it's just that white cultures have had the guns, germs and steel on their side.

that may be true but the op is still wrong or not making any sense. Just because it is something that has been going on for centuries doesn't make it right. And racism added fuel to the fire by claiming all black people were to be slave from birth till death like pets and farm animals. After 400 years of this treatment I don't see anyone in there right mind who wouldn't be a little angry at the idea and the people who were involved.

Right and wrong don't really exist. Slave traders were/are acting in their own contexts, since I doubt human rights treaties/philosophy existed in the 1400s. Persons in early modern times didn't even endorse social equality, as the concept of the three estates of the realm was the political/social order.