I think they were potentially referring to Native or Indigenous American genocides in the Americas. When the Spanish and Portuguese Catholics came they justified enslaving and genociding the natives under the justification from the Spanish monarch at the time that basically Catholics (interestingly of any race/ethnic group) were not allowed to suffer under slavery or be slaughtered... but non-Catholics weren't protected under this decree/law/whatever it was.

This actually is credited with the "invention" of racism as we know it now days. If anyone could theoretically convert to Catholicism and escape slavery, that was bad for the slavers. So they slowly moved over to a race-based, ethnicity-based system of chattel slavery where one's ancestry determined one's place in the world forever with no chance of upward mobility. Obviously the English and other first European settlers in what became the United States took the racism to the inevitable maximum endpoint and now over 150 years out from the formal abolishment of chattel slavery the effects of the racist systems still remain.

Anyway, I think if the reference was to Gaza or Palestine the more correct statement would be "because they aren't Jewish." Because that's ultimately the "problem" for the state of Israel and their pursuit of a permanent Jewish ethnic/religious majority. Palestinians could believe in Hinduism or Christianity or whatever else but at the end of the day the "issue" is they aren't Jewish. Just like white supremacists are concerned only with white/non-white dynamics. Acknowledging this also demonstrates why the "it's an ancient war!" idiots are dead wrong. Well, another way of demonstrating that fact. It has nothing to do with what they are and everything to do with what they are not. Again, the same as white supremacy. You're either white or you aren't. You're in the protected oppressor group or you aren't