I think all these cogs will be threaded. The two photos are clearly from the same photo session with the beads etc. And you can see in the photo that the cogs have the tip of the splines chopped off in a circle, unlike the chainrings. I.e. I think they're threaded, only the pic isn't sharp enough to see.
Have been wrong before, though.

The fun part is that you pay for the threading when you buy one of these things...

Edit: or not. In the linked pic, 3 are threaded, one appers not to be.