As I said before, it is simply a non-wage benefit, and it's a non-wage benefit that has a cost. It's a cost in the total compensation package of employees.
I know I'm repeating myself, but what's happening here is that the average total compensation cost—and that includes non-wage benefits of federal employees—is now totally out of proportion with the average employment cost of a private sector employee with similar qualifications. The best way to resolve that problem is to reduce a little bit through time some of the non-wage benefits, and sick leave is definitely a great place to start.