I don't think any laws were violated, and I understand the oversight justification in general. However, I find this salary data is fairly specific, when compared to other budget/spending data released by cities and school districts (at least my local ones). I'd actually prefer much more detail on non-payroll spending, particularly with public spending on sub-contracted companies.
I work in Higher Education and every few years the local newspaper in my area posts our salary information on the web, just in a less visual way.