There's a clause in there that will force federal workers to pay an additional 5% of their paycheck for their own pension fund. The current setup some workers pay 0.4% and some pay 4.4, it depends when you were hired, under the new system it's 5.5 or 9.4 percent. But it's "voluntary" you can get out of paying the extra 5% if you sign to waive your rights and become an "at will" employee. Then if they fire you, you're not allowed to appeal except in very specific situations like sexual harassment or racial discrimination.
So they're running a protection scheme, you pay for more for your benefits or we're going to demand the right to fire you any time we feel like it