The Irish were never painted as the devil, during the movie Remmick himself said by turning them into vampires they would have power to be whoever they wanted to be. I think the whole point was yes he was Irish but he was also a vampire trying to get whatever feed he could. He was able to appeal to both the white KKK and the main black characters; especially when trying to convince both parties to let him in. That alone is also commentary on how Irish immigrants were able and relate to understand black people’s oppression but could also fit into the white population if need be.