Unpopular opinion: when a club and a player enter a contract, they both take risks - especially when it comes to multi-year deals.
On the club side, there is a chance the player will underperform, or get injured.
On the player side, the situation at the club might change, key players leaving etc.

There are also advantages, especially for the players: wage is guaranteed regardless, cover in case of injuries etc.

For the club, the only advantage in breaking the contract of a key player would be a substantial transfer fee (and I think the Jets rarely refused international transfers).

Let's not pretend the players don't know this when they sign a contract: everything comes with a risk (ask Scottie Pippen). It's too easy to just cry when things don't go their way - it was part of the initial deal.

That's why I think it was a mistake to let Ibini go to another Australian team: now a precedent has been created, the club is weak from this point of view.