The people who know about ACL rehab say that it takes close to a year for the tendon to achieve full strength again - the period from 5-12 months is actually dangerous as it feels sound but the tendon is not strong. So he was always at elevated risk if he was to play this year after 5 months. Don't kid yourself otherwise.
Heard on a podcast (I think the Age footy podcast) that the record of AFL/VFL players who have came back early is terrible - Dale Morris the most recent example. Liberatore Senior got away with it, coming back in 4-5 months and one other that I can't remember. The Ox was another who famously did it again when coming back early - after a rehab of three months! There are others no doubt.
LARS allows you to come back faster but there are other problems and high risk of reinjury even with LARS.
So high risk of a reoccurance, lack of match time in 2019, risk of being a player down in a final all played their part I'm sure.