I don't think many people in the British Isles have ever heard about "mud" as having some kind of racist meaning. No doubt if it really catches on in the States it'll come over here too.

Meanwhile, we've still got the hippopotamus song: "Mud, mud.glorious mud..." And a search of the DT using "mud" throws up 73 entries, and I don't think any of them have a racial significance, so I don't think this is a word we should abandon to some racist fringe in one corner of the planet.