I'm pretty sure it is the operator, at least most of it.
After riding on 2 wheels for a bit over 50 years, a really LOT of things become automatic.
You don't realize how much until you get on something that has an entirely different steering "geometry" and stability requirements........like a riding lawn mower with steering "bars" or a motorcycle with 3 wheels.
You CAN teach an old dog new tricks but if you first have to UN-learn some old tricks it becomes MUCH more difficult.
I think I need more miles on the Spyder......and to finally get rid of my Vulcan and stay off of 2 wheels during the transition.
Younger riders may be able to do both but I think it's pretty obvious that I can NOT.