Firstly, I certainly hope they don't rush him back ahead of time. Absolutely need to play the long game - and make sure he can get a full pre-season under his belt. That should be the priority at this stage in the season.
That said, it looks likely that Lobb will leave at the end of the year. The coaching team may well be aiming to have Amiss in the starting 22 in 2023, or at least to have him play good chunks of AFL level. If thats the case, then a few extra games in the WAFL may well help him in his prep to round 1 2023. Fitness and strength is defiantly one aspect for a key forward, but so to are contest/body-work, executing movement/leading patterns, and mental preparation. You can't hone those in the gym.