Hi and welcome!
The dogpowered scooter is a great way to give your dog exercise, but... be carefull if you start now! You say your dog is only 5 months old, so he is still growing. When you have him pull you and the scooter, you put a lot of pressure on his body. Something he can't handle yet.
I wouldn't recommend having him run like that, untill he is at least 10 months old. And even then I would start him just walking/running besides the scooter/bike but not pulling it.
And keep your sessions short at first. Build up slowly.
If you have a bike, you can start now, by getting him used to walk next to it.
You say you are afraid he will pull you off the bike, well he can get scared when attached to the dogscooter as well and pull it from under you.
So it is important to teach him that this thing is not scary. You can start by walking next to your bike and having him next to you.
About him not liking strangers, well that is a bit off their nature. While some husky's are very peoplefriendly, some just aren't. Give your dog the time and space to get used to people, educate people on how to approach your dog. Most dogs don't like it when a stranger just comes rushing in to greet them, but we want them to like it. Let me tell you, when a stranger come up to me and touches me, I will back away too and look at him like: who the heck are you???
Tell people who would like to pet your dog, to make themselves small, by kneeling down. Don't let them pet him on the head, but on his side or under his chin(this is less threatening to a dog) Have them extend a hand, so he can choose to come in and sniff. If he doesn't want to, then that is too bad for the person.
It is ok to say your dog does not like to be pet by a stranger.
Most of the time, if the dog is ignored by the person, he will come in and sniff. On his own terms.
Don't pressure your dog into being pet by people, it will only make him more wary.
I am talking from experience, i also have a dog that does not like to be pet by strangers. Once the stranger has ignored him, he will come and sniff and when this person has been with us for a while(like ten minutes or so) then he will allow him to touch.
I wouldn't make a big deal out of it, as long he is behaving(not growling/barking/lunging) around people. If you can take him to a crowded place and walk him through the crowd without any problems, then there is no problem.
