The fork steerer tube type fitted to a bike doesn't matter, whether you use a threaded or threadless the fork, as long as it's the correct size/type to fit the headset/stem fitted.

The only reasons why you bike doesn't have a threadless steerer from new, is, as they weren't widely fitted till around 1994/5 & Kona were very late adopters of the technology (1997), which indicates your bike was produced in 1996 or earlier,