Because Cameron has rotated his Rucks consistently for 2 or 3 years, and Flynn was very good in the VFL, think its a near certainty to continue when Preuss is coming off an interrupted pre season and terrible historical durability aswell, common sense to manage his body through a 22 game season.
Did some research into Preuss regarding his poor durability :-
2017 - played 8 games in total, rounds 1 through to 4 & rounds 19 through to 22. So both times a block of 4 games in a row
2018 - 0 games played
2019 - played 7 games in total, rounds 4 & 5, rounds 16 through to 18, another game in round 20 & a final one in round 23.
2020 - played 3 games in total, rounds 12 & 13, another one in round 16.
2021 - 0 games played
That is some injury record.... a maximum of 4 in a row in his career so far & that was way back in 2017, big risk to lock him in at R2 with no long term cover (if you have English in the fwds that you can swing up through Hayes at R3 for example then maybe...) along with Cameron's rotational ruck policy as you mention.
I do feel the more prudent approach is to be patient, see how he goes v Freo this week & see if Flynn is picked/ if so, how much does that hurt his scoring.
Obviously we need to take some risks to get ahead in this game but not reckless ones, brave coach to take Preuss as your R2 with no adequate cover - I really don't think we can back his body in given that record. I think a conservative approach with him is the right move, I would feel more comfortable with him at R3 as a cash cow than fielding him incase he did go down early in a game which he has done many times in his career so far. With Ryder now back fit, Hayes maybe in trouble so a Hayes > Preuss trade to take the R3 spot appeals to me next week depending on their performances on the weekend & team selection.