Hm...
I assume custom requests would either happen realtime-- in which case it's not currently possible to substitute AI video output-- or asynchronously-- in which case the proof of personal connection eventually happens during a future realtime video stream.
If the customer is paying for DM'ing during times when the person isn't streaming, I'm having a hard time imagining why it would matter whether AI is used or not. Well, at least if the quality is decent enough for what I imagine are rather terse, domain-specific DMs. :)
You'd be surprised. A lot of men really do just have no-one to talk to.
Which is not the case currently, you think you're talking to your favorite porn actress but you're talking to some dude in India pretending to be her and trying to sell you "exclusive content" (i.e. prerecorded videos from a catalog).