As far as I read the article the tweet linked, it is the Council that makes a decision to sanction, on a proposal from the Commission.

And if it is limited to sanction foreign entities, I assume that if somebody in EU would do a "Today in RT" web page and just quote liberally fron rt.com (which they reach through a VPN), they could presumably not be sanctioned as they are a EU domestic entity. Put ads on it and you have a commercial enterprise. Might trip over copyright legislation though.