May I offer a word from an HR perspective?
You may be working against yourself in trying to get some form of closure on this issue. This is the sort of thing that dies away if left alone. You may be the one who's keeping it alive by forcing the issue.
Okay, you're not a racist. I accept that. I believe you. But by trying to force everyone else to acknowledge that, you are quite possibly just pushing the idea deeper into everyone else's mind. You may be working against your own best interests.
Unless you have suffered some definite damages - a demotion, a pay cut, the loss of a promotion - by this, you very well might find that you're best off by dropping it altogether. Just because they removed you from that particular contract doesn't mean the company doesn't recognize that you were in the right and the liason was the one out of line. Sometimes that kind of action is taken just because it will shut the other guy up. It doesn't mean that the company actually BELIEVES you're a racist.
Here's what I would suggest. Ask to see your personnel file. In your state they are not required to allow it but many, if not most, companies will. (If they refuse, that does NOT mean anything whatsoever to do with this situation. Companies that refuse this request do so because they believe the file is company property - not because they are trying to hide anything from you.) See what, if anything, is actually in your file. If there is nothing, DROP IT. You're only hurting yourself by raising the issue.
If there is something that directly relates to this, THEN come back, tell me what it is, and I'll give you my best judgement call on how to proceed. It will make a great deal of difference whether it says, We took warholsky off the ABC contract in order to keep the liason quiet, or We took warholsky off the ABC contract because he is showing discriminatory tendencies.
Trust me on this. I've put in a lot of years managing situations like this.