It's easy to see why Islamists looking to elicit the support of infidel leftists would glom onto the word: were Muslim Israel-haters to come clean and say, "The truth is that we hate Israel because it's Jewish and because of what the Quran and Hadith have to say about 'the Jews," they likely wouldn't elicit the same avid support that they do when they accuse Israel of having practiced "colonialism" at the expense of "indigenous" Palestinians.
The charge of "colonialism" is like a big stick that both leftists and Islamists can deploy to throttle iniquitous Zion even though historically, as Daniel Greenfield points out today, it's actually the Muslims who engaged in the "c" word:
Muslims invaded, conquered and settled Israel. They forced their language and laws on the population. That's the definition of colonialism. You can't colonize and then complain that you're being colonized when the natives take back the power that you stole from them.
There are Muslims in Israel for the same reason that there are Muslims in India. They are the remnants of a Muslim colonial regime that displaced and oppressed the indigenous non-Muslim population.
There are no serious historical arguments to be made against any of this.
The Muslim conquests and invasions are well-documented. The Muslim settlements fit every historical template of colonialism complete with importing a foreign population and social system that was imposed on the native population. Until they began losing wars to the indigenous Jewish population, the Muslim settlers were not ashamed of their colonial past, they gloried in it. Their historical legacy was based on seizing indigenous sites, appropriating them and renaming them after the new conquerors.
The only reason there’s a debate about the Temple Mount is because Caliph Omar conquered Jerusalem and ordered a mosque built on a holy Jewish site. The only reason there’s a debate about East Jerusalem is because invading Muslim armies seized half the city in 1948, bombed synagogues and ethnically cleansed the Jewish population to achieve an artificial Muslim settler majority. The only Muslim claim to Jerusalem or to any other part of Israel is based purely on the enterprise of colonial violence.
There is no Muslim claim to Israel based on anything other than colonialism, invasion and settlement...