Oppressive? Probably not so much. Divisive? Absolutely.
He was no better than the media that created fake stories about "hands up, don't shoot", and the entire Trayvon situation. He did nothing to diffuse the hate those issues created.
I'd say divisive. I'd say incompetent. Not so sure about racist. And I'm not even sure how that would apply to the facts dug on the Ferguson PD, unless Holder himself led the investigation, complied the stats, and wrote the report.