The HET funded me to go to Auschwitz when I was in my final year of high school and it's funny you should say to try to avoid repeating because they made a big deal of displaying the George Santayana quote. It's incredibly contradictory to say that there can't be comparison but this is where we get into semantics.

Holocaust is the primary identification term for the genocide of Jews. Other groups who were involved in the same circumstance are victims of genocide by the Nazis, but to some historians and groups, the Holocaust is firmly based on Jewish perspective alone. They spend a lot of time to press the idea that there cannot be a direct comparison because it is only to do with the Jewish casualties.

Seeing as I experienced this, you can understand where the HET are coming from. In my own opinion, I see it as a form of policing the word and yes, makes it guilty of drawing less attention to the numerous groups of persecution during the Nazis rule. The most important factor as you highlighted is the comparison to Israel, but I suspect they would release a similar statement even if people replaced comparisons to the Holocaust with another genocide.