So I got to T4 Diplo with one of my fed characters and grabbed a Nausicaan tac boff to send to another of my characters to fit with his theme, and it's telling me the boff is bound when I try to mail it even though it does not say it's bound, and did not say it was bind on pickup when I chose it from the diplo award store. If there was going to be a change to make them bound there should have been appropriate changes made to the in game descriptions to reflect them being bind on pickup.
I'm mostly annoyed because had I known they had been changed to be bound I would have picked a different boff on that character. That one is useless to the character I picked it up on, so I'm stuck with a boff I can't use and no way to get another one. That and if I do find a use for it I'm unable to have it trained in any of the player trainable skills I'd want, which further makes it useless to me.
I wondered this too some months back. I saw the Orion Boffs going for 100mil each, so I worked like hell to reach Diplomacy #4 only to find out (to my horror) that the Boffs were bound.
Those you see on the exchange are the ones that subscribers acquired from before the change was made, thus anyone who still has one can sell it on if they so wish. That's why some can be found on the exchange; they're the same Boff, just one is before the update and thus not bound, whilst the current ones are stupidly bound.