The problem with these things is that you can’t just go off of “Did the person do something bad?” (which, I think it’s fairly clear, these people did). If you want to prosecute them, you’ve got to have a solid case untainted by procedural compromises and blatant biases.
Say they genuinely were targetting black caucus members only. Suddenly everything in your case is tainted by racism. Maybe deals were made or evidence tampered with or a thousand other little things that mar the strength of the case. Or maybe they weren’t, but good luck convincing a jury (especially a Philly one) that the investigation was only racist in one thing but not in other.
Also, can you demonstrate a quid pro quo? If not, the worst you’ve got is a failure to report “donations” and “gifts”. Which, at this level of money, isn’t likely within the Feds’ threshold of interest.
Now, I’m not saying that Kane definitely didn’t engage in a whitewash for political reasons; I’m saying that we need to know more before we can be definite. And I agree that Kane should explain this in more detail; there’s no apparent reason to be cagey about this.