This seems to suggest the name comes from something else, but it is not written clearly and there is a reference to 'his name' which I don't understand. May be worth checking the other 4 .
Name
The sea's name appeared in George Windsor Earl's 1837 Sailing Directions for the Arafura Sea which he compiled from the narratives of Lieuts. Kolff and Modera of the Royal Netherlands Navy.[3]
It has been suggested that the name Arafura is of Portuguese origin, a corruption of the word "Alfours", meaning "free men", but recent research at the Dutch National Archives has revealed that AJ van der Aa's 1939 Toponymic Dictionary records "the inhabitants of the Moluccas called themselves 'haraforas', translating 'Anak anak gunung' as 'children of the mountains'."
European recording of his name dates back to at least 1663 when Blaeu records in the texts on his wall map of the East Indies "Archipelagus Orientalis, sive Asiaticus", that the inland inhabitants of the Moluccas call themselves "Alfores".[4]
The Arafura Sea name is from the indigenous name for "the people of mountains" in the Moluccas (part of Indonesia) as identified by Dutch Lieutenants Kolff and Modera in the 1830s.[3]