Oh CTOFN, I hope we haven't upset you or made you feel criticised.
I think the issue here is that you are not thinking about your pup's motivation, you are simply dealing with the behaviour. It's like treating the symptoms when you need to address the cause, IYSWIM?
Growling and baring teeth, unprompted and when approaching a family member who isn't paying the pup any attention is not aggression. It is a sign of a pup expressing a behaviour in the hope of a reward (in this case your DH's attention) - either because he's testing out new behaviours or because he's previously found that growling and barking achieves a reaction. The pup's motivation isn't to randomly attack or frighten your DH. Its motivation here is to prompt your DH to respond. The nature of the response is irrelevant. A response of any kind means the behaviour has been successful.
Once you understand that the behaviour is normal but undesirable you can cause the behaviour to die out by ensuring it goes unrewarded. IME the lack of a reward (in this case ignoring) is as successful and quick a way of training a little puppy as using any form of aversion (eg grabbing its muzzle), and is much less likely to have side effects such as causing a puppy to become headshy or fear aggressive. Why would the pup even bother to keep barking and growling at your DH if your DH simply ignores it? I reckon you could have this behaviour gone forever within a week provided the pup consistently receives no response.
This period is about building trust and establishing boundaries. Once you can identify your pup's motivation you can establish boundaries by absolutely removing any form of reward for unwanted behaviour - nipping, growling, barking, anything. Ignore, ignore, ignore - walk away and close the door behind you if you have to.
I've gone on a bit here but I really don't want you to feel attacked, I just want to help you understand A) why your pup is behaving this way and B) that your pup is not inherently aggressive. What you describe has no hallmarks of aggression and does not require punishment. IME the fear of aggression on the part of the owner is, ironically, one of the most common causes of fear aggressive dogs - because the owner has misinterpreted normal puppy behaviour and sought to punish it.
I think I mentioned this on your other thread but IMO the single most useful resource for novice puppy owners is The Idiot's guide to Positive Dog Training by Pam Dennison. It is modern, comprehensive and teaches you to "think dog" unlike many other puppy books. I would be astonished if the advice there does not echo the advice from your APDT trainer.
I am sure from the commitment and dedication you have shown so far that your efforts will be rewarded with a lovely family pet, provided you leave behind any notion that your puppy seeks to overcome you