Yeah that makes me nervous.

If you're using extra fork threads to keep your stem's max height/min insert line buried, you might end up with the wedge/cone in the bottom of the threads, and that's a recipe for a busted steerer. That line was designed to keep the wedge/cone below the bottom of what could reasonably be expected to be the bottom of the threaded section. In other words, it is not to protect the stem as much as the steerer.

I'd recommend making good and sure by measuring that that stem's wedge is well and safely below the bottom of the fork threads. Sure would be a shame to have that fork crack open.

Really cool bikes, BTW!