Write Mother Harley and report you've got a rideability safety issue that the dealer is refusing to address under warranty. Then suggest your next step is to report this lack of warranty support toward a safety issue to the DOT ( https://www-odi.nhtsa.dot.gov/ivoq ). Then forward a copy of that letter to the dealer.
The sentence following all that should be, "Then they'll adjust the damned neck." Trouble is this is Mother Harley, the patron saint of arrogation, so who the hell knows what will happen. It's still what you should do though.
Don't wanna Hijack this tread, but need to make a comment.
I just had the same thing happen to me.
One hell of a wobble at low speed. They blew it off first service. (Free at my dealer)
Didn't dare let my grip go for fear of it.
They told me it was with in spec!!!
I told them I didn't care, it was unsafe.

So after telling him how I really felt, I stated.
That's fine then, just put that on the work order and I will sign it, as the work order is a binding contract!!!
He was like (HUH). I said yep, just jot down that my concern is not really a problem, then when I wreck, if I survive, I will be your new boss!!
He then said, I will see what I can do.
Low and behold, he calls me back several days later telling me they did tighten the bearings for me, but they made them over spec.
I have put 1000 on since, rides great!!!!!!!!!!!!! Low speed wobble is gone and it is just better handling all around.
Damn shame I had to do all that to fix a known problem.
Hope this helps anyone else with this same problem.
BigDave