It's an old, old phrase you otherwise never hear these days ... apart from some rather clueless Tory MPs.
In one of his films the great W. C. Fields euphemised it as "the Ethiopian in the fuel supply."
In context I can't bring myself to believe that the phrase was intended in a malicious, that's to say racist way.
I would chalk this one up to thoughtless old-fashionedness, not racism. Never ascribe to malice that which is better explained by cock-up, as they say.
To me the far more distasteful thing is the collective professional outrage and lynch mentality of the rentagob MPs quoted in the article.