I'm not a fan of LLMs, but an app has absolutely no business deciding what input method I use.
This feels too similar to completely idiotic practice of blocking the copy-paste of credentials and disallowing password managers in certain apps/websites.
Not sure how those AI apps work, but it would be a shame if this boils down to a list of google approved input apps, like gboard or Samsung keyboard and anything else gets blocked.
My guess, without reading the article, is that they will just require input apps on the Play Store targeting Android 16 with AI features to respect some sort of allowAIInput = false flag
I'd wager side-loading and 3rd party app store apps will be ignored, but those apps will probably do it anyways to keep their Play Store releases.