I guess an uncharitable way to read this might be “the ML engineers/scientists want to automate all of the jobs except their own.”
Getting major deja vu from like 10 years back when people were arguing 3D printers would 3D print other 3D printers.
Insta-job security.
The charitable read is that their restrictions for "safety" (i.e. what's separating Fable from Mythos) makes this inevitable. If you could just make your own Mythos it would circumvent the protection.
Which kinda just highlights how weird this situation is.