That is weird indeed. Especially since there are regular scheduled flights from the Reykjavík airport[1] to Kulusuk. Reykjavík airport is included, along with most airports that have scheduled flights from there (like Ísafjörður and Egilsstaðir) but not Kulusuk.

[1]: not to be confused with the larger Keflavík international airport that handles almost all international flights to Iceland