|Message:||I think Joey must be very bonded to you, and insecure with everyone else. You probably interact with him the most? There's no fast way to fix that, but you can get him to eventually become more accepting of others. Just have your friends and family spend more time with him. He'll be most comfortable with those he knows best. Try to get others involved with him when you are not around, let him develop new routines with other people. Ambient attention is good, just having Joey around on a playstand with other people nearby. It's great if the others occasionally say hi, or feed him a treat. You can also do a rescue scenario, where you put him somewhere unusual (where he doesn't feel quite safe) and walk off. Someone else can come "rescue" him and bring him to you. Always, make sure no one scares him, and be patient.
Now for your other question - My macaw does the aggressive beak wiping, but it is very obvious. Maybe she's learned to exaggerate the behavior for us dumb humans, I don't know. She bends down, raises the feathers on her back and neck, and rubs her beak on the perch, all the while keeping aggressive eye contact with whomever she is threatening. Alternatively, she walks along the perch dragging the tip of her beak on it until she gets to the end, and then bites the end, giving you a look like "Yeah, I wish that was your finger." LOL
I haven't really seen my nandays do the beak-wiping as a threat. A threat is in the way they stand, the way they look, their feathers, their posture. This beak wiping seems to be more like an "irritated, here now, moving on to another activity" or "I'm all done with the food and need to wipe the goo off". Of course that may be something of a learned behavior, in which case your boy and my guys may be doing the same thing for very different reasons? Oh, and one of my rescues used to do this pathetic pose, hanging on the cage bars and madly rubbing his beak over a horizontal bar. In his case it was a weird, aberrant thing that he did only because he was a neglected bird with no toys for several years.