Rams defensive tackle Aaron Donald has indeed returned, and the team has reinstated him to the roster. But the Rams didn’t have to make a corresponding roster move to create a space for him.
The Rams have received a roster exemption through September 18, which allows them to carry 54 players through Week Two, if they choose to do so.
If the Rams decide to activate Donald before Week Two, they’ll have to remove a player from the roster.
Donald will play when ready; he definitely won’t be playing in Week One. He could play in Week Two.