I'm more than a bit baffled by this idea:
Despite the fact that Ron Paul, through his profitable, base-building newsletters, has actively spread and reinforced racist ideas, the really important thing here is that an end to the war on drugs would do more good for African American men than anything else. And since Ron Paul would, if elected president of the United States, end the drug war, anyone concerned for the welfare of African American men really ought to be in his corner, whether or not he has cultivated financial and political support through racist agitprop.
One obvious difficulty with this line of reasoning is that Ron Paul will never be elected President of the United States, and has about as much chance of ending the drug war as I do. He is little more than a symbol for a set of ideas—ideas his complicity with racism has tainted in many people's minds, whose prospects he may have damaged. I want to end the war on drugs, therefore I'd rather people not associate that idea with Ron Paul.
One of the embarrassments of the American libertarian movement is its failure to sufficiently acknowledge how collective bias against blacks, women, gays, immigrants etc. deprives blacks, women, gays, immigrants, etc. of their freedom. To my mind, serious forms of structural discrimination are much worse for liberty than certain kinds of coercion. Libertarians make themselves look ridiculous when they claim that everyone is fully and equally free as long as no one is coercing anyone. Now, this isn't obvious. At least it wasn't to me. It took me a good while to come around to this view—to see just how much structural bias does deprive people of their freedom or of the value of their freedom. But I am embarrassed that it took me as long as it did.
Here's where I'm coming from philosophically. I am no Rothbardian or Randian. I do not understand the argument that concludes in the categorical prohibition of all coercion, but which permits some other things far more harmful to the pursuit of happiness than most ticky-tack government regulation. I agree with some aspects of the 19th century criticism of classical liberal freedom as “merely formal.” I believe that the liberty most worth caring about is positive liberty—the ability effectively to enact one's plans, to achieve ones ends. In my judgment, a regime of strong negative rights is the best guarantee of positive liberty. Government attempts to guarantee the worth of our liberties by recognizing positive rights to a minimum income or certain services like health care often (but not always) undermine the framework of market and civil institutions most likely to enhance liberty over the long run, and should be limited. But this is really an empirical question about what really does maximize individuals' chances of formulating and realizing meaningful projects and lives.
Within this framework, racism, sexism, etc., which strongly limit the useful exercise of liberty are clear evils. Now, I am ambivalent about whether the state ought to step in and do anything about it. Maybe I'll get into the complexities of that question some other time. What I am not ambivalent about is that racism and sexism, etc. deprive many millions of Americans of the full value of their freedom. Insofar as Ron Paul's racist newsletters propped up and encouraged racist norms, he has actually helped cultivate a cultural climate hostile to the prospects of “the blacks”, whether or not he would end the drug war in the miraculous event of his presidency.
In my opinion, it is the responsibility of decent people concerned with liberty to at least denounce, if not actively work to tear down, the racist beliefs and norms that enable liberty-killing structural discrimination. If you don't think ending discrimination is the government's job–that this is the sort of thing that should be done by persuasion, not force—then you should take this responsibility extra seriously. It's your job to persuade. If you think the government should do nothing but stay out of the way, but you are indifferent to racism and people who publish racist newsletters for financial and political gain, then it is not unreasonable to conclude either that you don't really care about other people's liberty, or think racism has nothing to do with it. In either case, you would be wrong.