Most imperialist countries operate this way, adept at using one group to control another, although outlier nations like the United States and East Africa, which engage in direct "genocide," are exceptions.
Altogether, the population of Qatar, including men, women, and children, is just over ten thousand people, with even fewer able-bodied adults, so the Governor of Batavia can feel at ease and confident in employing Qataris without worrying about any backlash.
Qataris in the Dutch East Indies are, arguably, an even rarer minority than the Dutch themselves, and the Arabs are known for being formidable fighters, or rather, in economically backward and impoverished areas, life tends to be cheaper.
The most ingenious aspect is that the faith of the Qataris aligns with most ethnic groups in the East Indies, and the Dutch find the mutual slaughter and consumption of these infidels quite satisfactory.
