Buying/Selling Koins

[Justice]

Are Koins allowed to be sold / bought from other users now?

Help documents say:

Where can I purchase Koins?
Koins are no longer available for purchase from the site. However, you can purchase them from other users. You can purchase Koins from other users for a 1:1 ratio.

And the Koin Exchange section:

Rules
Buying/selling Koins is not allowed.