I agree with your opening sentence and I think that the OP’s comment about rising wages due to the lack of skilled migration in some industries may be a big contributor to the rush, on the part of politicians, to open up as well.
Wages stopped increasing consistently years ago across the economy and one of the reasons for it is almost certainly the availability of workers from outside Australia which gives employers access to a workforce many times larger than the number of people who have received training locally.
It feels like industry groups have given up on discussing ways to train a local workforce whenever there is a labour shortage and leap straight to demanding that governments at all levels allow them to simply import the workers they require instead. This stops local workers from using the scarcity of their skills to ask for higher pay and negates any need for employers and industry to look ahead at their future labour requirements and invest now in training and up-skilling the workforce.
If closed borders result in employees receiving their first decent pay-rise in 8-10 years, voters may be less keen to go back to business as usual and I am sure politicians and employer groups are aware of this.