Since it's the user's device, not Apple's, EU correctly "interprets" this as the user has the right to do whatever they please, including installing third-party chat apps.
Apple are just bulshitters when it comes to actual users, and not their corporate definition of a user.
BTW, did you know that in Japan, and in Japan only, you can change the Siri shortcut button to start other voice assistants? https://mjtsai.com/blog/2025/11/18/ios-26-2-third-party-voic...
Or that they wouldn't let you set default maps app outside of the EU: https://mjtsai.com/blog/2025/03/14/dma-compliance-default-ma...