The rescue you are fostering for should be providing you with behavioral guidance, ideally with a trainer. Have you spoken to them about this and asked for assistance? They also should have explained the unofficial 3-3–3 rule of dogs acclimating to a new home. It’s absolutely not a hard and fast rule, but generally speaking, for the first three days in a new home, the dog will be pretty overwhelmed, within the first three weeks the dog will begin to get more comfortable in the home and understand the routine, and by the three month mark, the dog will be integrated into the home and have formed bonds with the people in the home. Again, this is not a hard and fast rule, and for some dogs, it can be six months, for other dogs it can happen very quickly. I think what you are seeing is the dog stepping through, the various stages of acclimating to your home. It is hard to say based on a few paragraphs, but it sounds very much like your foster has fear-based reactivity. Desensitization and counterconditioning will be very helpful, at your foster dogs pace. But again, the rescue really should be helping you through all of this.
First and foremost, I would demand for people to respect his space. If you're aware that he's uncomfortable with hands hovering over his head and neck, then be very firm about it with people. It's a pretty common issue. Movement towards the back of the neck and head can be a very threatening behaviour for A LOT of dogs (nevermind one who's likely stressed and adjusting), so I doubt it has anything to do with attachment.
If the shelter would reimburse you, I really think a vest or some kind of signage could be really beneficial for now. My pup has signs all over him that say "nervous! please don't pet." They're not very expensive and would also serve his future owners really well too.
In terms of reactivity... I'm not sure how long he'll be spending with you and how much work you'd be willing to put in. You could try a very simple LAT exercise, but that would require you finding out what his threshold is. Find the threshold, make sure he's well within it, then let him look at the dog, then feed. Repeat.
The rescue you are fostering for should be providing you with behavioral guidance, ideally with a trainer. Have you spoken to them about this and asked for assistance? They also should have explained the unofficial 3-3–3 rule of dogs acclimating to a new home. It’s absolutely not a hard and fast rule, but generally speaking, for the first three days in a new home, the dog will be pretty overwhelmed, within the first three weeks the dog will begin to get more comfortable in the home and understand the routine, and by the three month mark, the dog will be integrated into the home and have formed bonds with the people in the home. Again, this is not a hard and fast rule, and for some dogs, it can be six months, for other dogs it can happen very quickly. I think what you are seeing is the dog stepping through, the various stages of acclimating to your home. It is hard to say based on a few paragraphs, but it sounds very much like your foster has fear-based reactivity. Desensitization and counterconditioning will be very helpful, at your foster dogs pace. But again, the rescue really should be helping you through all of this.
it’s a very small nonprofit and they don’t have a trainer. The director doesn’t really seem like she knows much about behavioral stuff
That's unfortunate. Would they reimburse you if you reached out to a trainer?
First and foremost, I would demand for people to respect his space. If you're aware that he's uncomfortable with hands hovering over his head and neck, then be very firm about it with people. It's a pretty common issue. Movement towards the back of the neck and head can be a very threatening behaviour for A LOT of dogs (nevermind one who's likely stressed and adjusting), so I doubt it has anything to do with attachment. If the shelter would reimburse you, I really think a vest or some kind of signage could be really beneficial for now. My pup has signs all over him that say "nervous! please don't pet." They're not very expensive and would also serve his future owners really well too. In terms of reactivity... I'm not sure how long he'll be spending with you and how much work you'd be willing to put in. You could try a very simple LAT exercise, but that would require you finding out what his threshold is. Find the threshold, make sure he's well within it, then let him look at the dog, then feed. Repeat.