I think when the author says "all-rookie special teams unit" he's just talking about LS, K, and P.
The Rams have a lot of guys who played special teams last year who are still on the roster, and may continue to play teams depending on where they land on the 2023 depth chart.
Among the returning STers are their top 3 guys (Rozeboom (373 snaps on teams), Hoecht (369), Rochell (325)). Added to that list are Yeast (6th most snaps on teams), Jonah Williams (7th), Lake (10th), Hardy (12th), Hummel (14th), Durant (15th), McCutcheon (16th).
There are other guys still on the roster who played some teams last year, but none of them had over 100 ST snaps. (The guys I mentioned did.)
Some of these guys might not play teams in 2023 if they move up the depth chart. But the Rams aren't afraid to put starters on teams - Ramsey (with 126 snaps on teams on 2022) and Ernest Jones (83 snaps) among them.
This is not to say that there won't be a lot of rookies who see the field on teams - there will be. There just won't be 11 of them at a time (like the title of the article might lead you to believe).
AlbaNY_Ram