It's often the case that something a denier presents makes you look at things in more detail and you find something new.
In this case a twitter user was claiming some nonsense or other about the views of Earth above the horizon at the south massif.
I looked at the photographic record and found that Cernan took two separate views of Earth over the imaginatively named 'Boulder 2', separated by about 15 minutes. That, I thought, should be just enough to detect some rotation. Well what do you know (you might need to click the image to get it to show the movement):
The images used are AS17-137-20910 & 20961. SkySafari's excellent Apollo mission app is included for the avoidance of doubt.