There are issues here beyond immersion. One of them is that so far, nobody can peek inside the GPT-3 NN and find out how the game devs trained it.

If a player got something extremely disagreeable from an NPC, was this a fluke or did a dev intentionally add it in training as to make it more likely? There's no way to prove innocence. Add in trigger-happy social media + governments, the potential cost to devs & publishers could get all the way to bans/boycotts/legal threats. Most companies do not wish to risk this, so mitigations must be in place.