After the prop master discussed with us that we had never seen the stock deployed on an E-11, even though it's shown on an official LFL book, i shot for 2 days on the set of Kenobi with my real Steeling E-11 and it was seen on screen.
We did this little photo as a mash up I called "For the Emperor" at our garrison photo shoot. I made the gladius out of an Ultramarines umbrella handle. If your not familiar with the Warhammer universe there is also an Emperor. Photo credit Michael Bender.
I think the writer is confused and doesn't know the facts. The only 501st member was there in his professional stunt capacity. They're all stunt actors in that shot aside from Hayden.
In the wide shot where Kenobi is on his knees, Third Sister in in front of him and all the troopers are aimed at him, on the left group back right, the stock is deployed in that scene as well.