Judging from the ad, this is being sold by the storage facility which means they are invested in getting it gone.
This could work to your advantage as, obviously, the bike is not road-worthy right now.
I think you should call the seller and take it for a test ride. When they tell you that it cannot be ridden, that gives you a bargaining chip right there.
If they don't budge on the price, you haven't lost anything except a few minutes on the phone call.
With all the upgrades to the bike, this was certainly someone's prized possession, I think it is definitely worth looking at.