No, a federal employee can punch you while carrying out their job and the federal government does not get into legal trouble. (Is the way I understood it from reading the post above.)
If punching someone* is within the scope of their employment by the federal government and the person doing the punching is not a law enforcement officer, you cannot sue that individual for intentional torts.
*not sure why it would be, if you weren't a law enforcement personnel
An example is a military servicemember or police officer who needs to assault you to prevent you from assaulting someone else. Normally you could sue but because they're preventing you from committing a crime by use of force they have immunity.
Just out of curiosity, doesn't this leave a large loophole for extrajudicial gangsterism if the government created a job that included, say, punching people who didn't pay their taxes?