It is a genuine concern though. Certain Chinese laws do state that if the government wants, companies like tencent must hand over user data, including the data of foreign users outside their jurisdiction. Riot is owned by Tencent, with a CEO that is a card-carrying supporter of the CCP.
Personally, while I think the developers at Riot didn’t intend for it to be a data-collection tool, the level of access it has could certainly be used as such if they wanted.