Also a misdemeanor, which is uncommon in federal court and likely viewed by at least the judge and defense as a nuisance to be disposed of.
And, in your typical, relatively complex federal prosecution, the prosecution has to do months or years of investigation, generating a bunch of evidence, most of which has to be given to the defendant and the defendant then has to have some time to go through it. Then you have your pretrial motions about whether the criminal statute really fits the offense and so on.
Most federal crimes are not of the simple, common-law type like assault, burglary, rape, murder.
Even in this case, though, it seems the defense did some pretty serious investigation to find that the agent had received gag gifts over it.
Long story short, this has no business being in federal court and everyone knew it.
What's interesting to me is that a DC jury took seven hours to acquit. That tells me that the jury took the case seriously despite being obviously political. It may have been a crazy holdout situation, but I think from the questions they sent the judge, they tried pretty hard to decide if the actions really fit the definition of the crime.
Final note, everyone involved had some recognition that trial time in a US District Court is a rare and precious resource. The defense doesn't really care as long as it gets its trial sometime in the millennium, but the judge for sure and the prosecution, probably, care quite a bit that 2-4 days of precious trial time are taken up by unserious, political cases.