Again, I disagree. Scholarly consensus has been moving towards the direction of inclusiveness (particularly for the question of the Roma and the disable). In fact, as you go through modern academic literature (the last 20 years), "Holocaust" more and more includes non-Jewish victims. Just an example: Alex Callinicos, from York University, (2001) The Holocaust isfor good reasons I need not rehearse heregenerally held to be the most extreme case of human evil. All the different kinds of domination fused together in Auschwitzracism, directed at Jews, Slavs, and Roma; the economic exploitation of slave labour; the oppression of gays and women; the persecution of dissenting minorities such as Communists and Jehovah's Witnesses. Or Slawomir Kapralski, "Identity Building and the Holocaust: Roma Political Nationalism." I have already mentioned Sybil Milton (who was a senior historian at the Research Institute of the US Holocaust Memorial Museum), and Henry Friedlander, a leading Holocaust historian in the USA, is another important voice. This increasing consensus has had an impact on common language , as well on political bodies. See this press release from the UN, for instance. It is not a question of ranking victimsit is the concept of hte holocaust as a racist, mordern project, and the common fate of the victims. The famous pictures of Mengele's twins are of Roma children. The technology and expertise for mass murder was developed for the disable in the T4. The tactics of Eisengruppen were first developed in the invasion of Poland, against Polish leaders. I have seen several good arguments that convinced me of the centrality of Jews in the Holocaust; I have never seen a convincing argument for their exclusivity.
If this is not enough, let me try in another way: by deciding to describe the Holocaust as an 'exclusive' Jewish event, wikipedia is taking sides in a ongoing scholarly debate (I could say on the 'declining' side of an ongoing scholarly debate). this is NOT holocaust denial, with no legitimacy in the academia, and it must receive more than mere lip service in the body of the text or in the footnotes. At very least Wikipedia must admit the existence of debate in the lead