1. The Nazis only killed "gays" if they were political enemies. Why the "gays" feel the need to "own" any part of the Holocaust is any body's guess.
2. The Nazis attempted the exterminate the entire Jewish race. They succeeded in killing 6 million of them, and virtually wiped out the Jewish population of Poland and Western Russia. You would probably want some sort of remembrance, too, if such a thing were to happen to your family.
3. The Holocaust claimed 11 million lives. Over half of them Jewish.
Being gay had nothing to do with being political enemies. Anyone who was not considered the Aryan ideal was genetically imperfect and subject to being "culled" from the master race. As far as ownership of the Holocaust, it was Jews who protested including any other group in this memorial. Even the word Holocaust seems to now longer apply to any other act of genocide other than the Jews in WWII.
BTW, there are those who would dispute the 6 million figure based on the population of Jews before and after the war.
The Holocaust might have claimed 11 million lives, but WWII itself is estimated to have claimed 200 million.
I am in total agreement about the Holocaust guilt thing. This was a horrible tragedy but, while I don't feel we should forget the past, I don't think we should have to have it shoved in our faces all the time. Once my sister was in a psychology class and her teacher showed a video of the Holocaust, which had NOTHING to do with the course of study.
Washington DC has a big Holocaust museum - why, I don't know, since it didn't happen there. There are Holocaust memorials in cities and towns all across the country - more so than in the country where it actually occurred.