They didn’t disclose it because there was no AI in the final product. The AI was for placeholder textures, which were replaced by real artists’ work as they were made. Some of the AI textures slipped through the cracks on release day, but a week 1 patch removed all traces of the AI before anyone even realized it was AI.

IMO this looks bad on the awards show, because the final product didn’t have any AI. And the production team was proactive in ensuring it didn’t have any AI before any kind of public backlash ever happened. Once they realized the issue, they issued a patch to fix it on their own, without needing to be pushed into it by public pressure. That’s what a company should do, and it shows that the devs really cared about their game.

The reason they didn't disclose it as being used in the creation of the game is probably because no AI was used in the ultimate development. It's an artist who uses AI to generate concepts and inspiration using AI in their artwork, even if everything in the end is hand crafted and doesn't resemble any of the generated images?

One thing we need to take into account going forward too is that AI will inevitably be used for things like texture maps and environmental generation. Things that have been randomly generated with algorithms. In a year it's going to be nearly impossible to say no game can have any AI used at all, unless you want the pool of potential to be incredibly small.