I imagine it's because they aren't authorised to speak for the company on topics like what government policies the company is against (and I imagine this is why you got down-voted).

But yes, I also would have expected Atlassian and other Australian-based technology companies to vocally oppose this bill because it will actually result in their customers moving away in the long run (this bill will only affect companies incorporated in Australia or other 5-Eyes countries) -- because this bill explicitly requires companies to architect security systems to be insecure. Unfortunately this doesn't appear to be the case, which is incredibly disappointing.