Maybe it was clear. Does that mean they should not make that choice?

“the question of exactly what Australian officials have been doing all
these years to make this known to their Solomon Islands counterparts.”

Maybe they have made it known. Is there any reason to suspect that
they haven’t, other than an expectation that the Solomon Islands will
do what Australia wants?

“It should have been unambiguous to the Solomon Islands Government
that this means Australia expects …”

Maybe it was unambiguous to them. Is that any reason why they should
do what Australia expects?

For now, in addition to deploying all manner of … sticks …,
the Australian Government must …

Considering whether the Australian Government has any entitlement to
“deploy sticks” would be a good start.

The writer’s obvious view that the Solomon Islands should do what
Australia wants, which seems entirely consistent with the view shown
by the Australian government in the past that Australia is entitled
to run Solomon Islands affiars, is quite likely the reason for its
diplomatic failures.