Note that Google, Apple, etc all have Australian employees and have subsidiaries incorporated in Australia. Google Maps came out of Google Australia, for instance. So you could argue they'd lose talent by pulling out.

Don't get me wrong, I want big tech companies to retaliate since that's the only way to get the attention of the Australian government (they stopped listening to the proletariat a long time ago). But it should be done as a retaliation, because that's the only justification that I believe would be consistent and might make a difference.