Like, here is a quick deepfake i did (10 min literally) of Ewan McGregor as Old Obi-Wan:
https://streamable.com/lltjip
It’s mediorcre at best. The eyes need more work, and Alec Guinness has a bigger face than Ewan, but this was 10 minutes without me pinpointing it in the right direction to fix these issues. If Alec Guiness’s eyes and beard were CGI, the deepfake would STILL look shit with the best of deepfakes because it would imprint on the computer-generated strains rather than the real-life human.
CGI Artists of 2016 just couldn’t replicate human eye movements and wrinkles around the mouth well enough for a plain deepfake on-top to work wonders, no matter if they had the camera for tracking. It just wasn’t precise enough. You can see this in the eye and mouths in Planet of The Apes movies as well (even the newest one). But of course they can’t deepfake monkey faces (yet) - and they’re not humans, so they get an easy pass.
BUT! With a CGI Mask made with AI (some of them are insanely good models for facial movements), you could replace the awful CGI MASK of 2016 with a 99% believable face trained on millions and millions of faces around the world. And then! A deepfake would do wonders.
And to bring this back to the main topic;
my theory is that they filmed scenes with Guy Henry for deepfake, but some in the production said it wasn’t far enough along and they opted for CGI. The irony is that the latter option would be so much easier to fix post-release (but of course this is not relevant to them, at least not at the time).
If they released Guy Henry’s POV shots from the camera that filmed his tracking dots, a 100% believable Tarkin could be produced (Luke in Mandalorian season 3, but better).