It's clear he's not getting a vaccination.
If we put him on the inactive list it's in the hope that:
(1) the AFL drops its mandate (you'd think start of 2023 at the absolute earliest)
(2) Darling is able to come back after 1+ year out of the game at over 30 years of age and have an impact which justifies his contract; and
(3) the loss of trust and confidence between Darling and the club (including otehr players) can be overcome.
That's a few big hurdles, none of which the club can completely control.
In reality the inactive list is just taking a very small risk for a potentially great reward.
I'd frame it as 'is the club willing to pay $30k p.a. for the next 3 years inside the salary cap, in the hope that JD will play for them in a future year'
if it was a developing player, or a fringe player, then absolutely not. But JD is up with the elite of the competition - $30k is a very small payment for that 'option'.
1 is unknown
2 I think it would be a safe bet he would return at AFL standard - maybe not 'as good' as he was, but good enough
3 they'll work it out. See what Dom Sheed said yesterday - basically if he is allowed back in the doors he'll be welcome. Maybe it will be a bit difficult for a few weeks, but adults seem to work these things out.