Have you considered the cost to that business from all the bullying, harassment, and racism? If these problems are endemic in Airservices as the union suggests, absenteeism, resignations, and lower productivity would be a massive cost to the business. You make some valid points Sunfish, but your argument is weakened when you refer to all these highly objectionable actions as 'thoughtcrimes'.
I'd suggest that you really haven't been in a business where discrimination and harassment prevail as part of the culture. I have, and it is/was an ASX200 company. It is extremely difficult to change unless the exec team get behind serious changes in structure to make it clear that in the 21st century that sort of behaviour is inexcusable.
Also, the Modern Slavery Act is not specific to the aviation industry. It exists to ensure that no matter where you are in the supply chain, you have an obligation to ensure that slave labour was not used further up the chain. As inconvenient as filling out extra paperwork may be for you, I know for a fact that in my previous industry (outside aviation) it forced some suppliers to truly audit their supply chain - which is overall a positive step. Some of the biggest businesses in Australia (think Wesfarmers) were unknowingly using slave labour in the manufacture of their products.