You're correct that Speed Demon was not there in 2016. It was my understanding that they already had the record (with a "C" motor) in the class where they'd be running. So, why bother?
I think it may be the same deal this year. With the "A" motor they ran initially at Speedweek, they would have been in an FIA class where they did not have the record.
However, i heard they hurt that motor, which left them with the "C" motor once again.
Maybe George is thinking about Bolivia now, too.
I'm pretty sure Danny Thompson would have come to the Shootout, too, if he didn't lose a rod in his front motor at Speedweek.