Underlying your position, is the belief that the main reason that African Americans face poorer outcomes than Asian Americans in aggregate is because they have faced more discrimination against them. You are unwilling to compromise in this belief.
You are using Asian's relative success against African Americans to argue that they must therefore not have experienced discrimination. This reasoning is backwards. You ought to first quantify the discrimination (you'll have to figure how to do that yourself) and then see if there's a correlation. Otherwise, you're arguing a fallacy -- a form of affirming the consequent.
If we were to accept your explanation, then we would be forced to conclude that other groups (such as the Hmong or Bangladeshi) who are doing as bad (or perhaps worse) than African Americans must have faced even worse discrimination in America in the past, which I think you'd agree is not true.