The union would believe Canada Post should be operated as a service first, but naturally it can be run as a business to make sure it's making money and staying sustainable, etc.
Again, what are the profits for? Where do they go? I mentioned that Canada Post has given $1.5 billion in taxes and dividends to the government since 1991. Maybe those dividends could be put back into expanding services to Canadians and finding efficiencies in the operations.
I think it should be service first and business second. One of the reasons the union supported converting Canada Post to a crown corporation back in the 1980s was to allow it to operate more efficiently and sustainably in the long term. Its track record, according to the profit statements from its own records, shows that doing that was a huge success.