McLeod is compiling the list because both the former administration and the current one have committed to publishing one but haven't done so yet. Several other provinces publish similar lists of public employees who make more than $100,000 a year.
The union's says it's okay to disclose the position title and income but McLeod shouldn't have the name of the person holding the job. It's a insane argument since there is no practical way to withhold either of the three elements of the request - name, position, salary - such that a person couldn't make up the list after a couple of requests. It's an insane argument from because the unions don't oppose disclosure of the name and position separately from the salary. Well, at least they haven't objected so far.
But the position taken by the unions doesn't make sense for a bunch of other reasons.