Speaking as an ex-federal employee and the child of a former federal employee, federal employees aren’t exactly in a bad financial or benefits position. Them not getting a raise is not going to be throwing them onto the poverty rolls and they will likely just end up getting the raise some other year or under some other President.
Anyone who doesn’t like their raises or their job being contingent on political maneuvers is free to go work in the private sector, but then they lose a lot of perks other than raises that federal employees get, such as job security that’s much better than what you get in the private sector, or resume-building job experiences you can’t get anywhere else.