Good lord.
There are a number of interesting things going on in your post, not least of which is you having a conversation with someone who does not actually appear to be myself. Let's just forget what the other guy said - if he feels like it, he can chime in, but, frankly, if I were him, I'd stay the hell away.
What I think, is that the impact of racism is magnified by the power of the group that is racist. What you're not getting is I'm applying this at the level of society, you're applying it at the level of a small group of people. At the low level, duh, of course the group of people beating on the individual have more power than the individual, whatever their race. But, move up to the level of the society as a whole - one of those two groups is going to have more power, that's the group who's racism will have the greater impact.
Think about it this way. Hypothetically say you have a society that is 10% one race, 90% another (notice that I'm not saying black or white - that makes no freaking difference). Say both races are equally racist towards one another. Say that tha majority group happens to have vastly more political/social power as the minority. What I am saying is that despite both groups being equally racist, there will be more racist acts by the powerful majority towards the less powerful minority than vice versa. And so, while each individual act is equally bad, there's more badness flowing in one direction.
So yes, it is just as bad and not as bad, as you so eloquently put it. You simply need to be able to look at the issue at the level of the individual incident and in the aggregate.
That said, since you concluded your well written argument by apparently using racist as a synonym for "I disagree with you," followed by the interesting claim that I had equated whiteness with racism, I suspect there's the outside chance that you will not quite agree with this argument. I welcome further, well reasoned, points.