You're right on this point. But there are ways to build interfaces that sidestep this.

Run a sanitized VDI with no local storage --> offshore independent entity (e.g. a Hong Kong Company) that holds the AI service contract and API license --> GLM-Legal.

Somebody ought to set this up for pro se work.

Yeah sure but your clever sidestep is just "hiding evidence from the court." The kind of person that feels the need to have a secret AI lawyer is also probably going to just tank their case in another way.