Quick query for you all. When you think of the term, "Mexican Culture", do Tacos, Sombreros, or Speedy Gonzales come to mind, at least for a brief instance?
If you think of culture in the Northeastern USA, do the Pilgrims or square dancing come to mind?
What comes to your mind when I say, "Potato's, Corned Beef, and Alcohol?
How about schoolgirls, creepy fetishes, and downright weird consumer products?
If you thought what I think you just thought, I am not saying your racist. I'm saying that you are susceptible to iconic images, a possible, but not necessarily, nor inherently wrong, precursor. When the human mind try's to encode a concept into its brain, it tends to latch onto certain mental shortcuts called Heuristics. Its easier to have a representative icon for some major concept. This is just a quirk of the human brain, and I don't think its fair to call foul on it until you turn this mental shortcut into a rule for actual people in real life situations.
Resident Evil has been shown already to use these Heuristics in its storytelling. Europeans get feudal weaponry, pitchforks, castles, and the like. There just going for storytelling that's easy to latch on to. We associate Africa with spear throwing warriors, and indeed this image is not completely absent from the continent. Its not the most bold storytelling tactic, but I don't think its racist.
On that note, because of the prevalence of racism in America, I think its completely understandable that RE5 will turn a few heads and rattle a few cages as people try to figure out the cultural ramifications of the game. Then, they will realize that the subhuman portrayal is representative of the undead, and not black people, and they will move on. All is going according to plan.
Lastly, Occams razor. The nameless NPCs in the game are portrayed as a sexual threat, and shown as bloodthirsty savages. Is it simpler to assume that this is A) An attempt at exploiting racist tropes to present racist political commentary, furthering some Anti-Black agenda that originates from a Japanese group or B) Because there what Zombies have always done.
This would only be Racist if it makes the implication of these behaviors in non-zombie NPCs. Gold star to you for being self-critical and trying to maintain social justice, now pick up the controller and explode some zombie heads.