with a steerer that long I suspect you need to clamp the bearings in with some vigor to ensure they don't dance around like a fairy with wind. Why you would choose 1" for it is a bit odd, but I guess weight savings could be claimed (like it needs it).Designer spent too long at bespoked. But they'd sold out of threaded king headsets.
I struggle with the appeal of an inch threaded headset on a modern frame
And good luck replacing that stem if you want one 10mm shorter
But it's still sexy