Valve has an official position that they don't allow AI content (apparently). When the lawsuits show up they can say that they don't serve any AI content as official policy. When someone points out the AI content that they do serve, then they pull out their expert witness that testifies that their AI detection method is as good as possible and they couldn't haven been expected to do any better. Meanwhile, they're more than happy to remove anything explicitly flagged that falls through the cracks.
Finally, I suspect that anyone who can prove that they're able and willing to indemnify Valve against lawsuits for AI content that their game contains will be allowed to have AI content.