Nothing to see here. Garden variety pussy prosecutors. Fed prosecutors don't take shit to trial unless they're nearly certain they'll obtain a conviction. Two acquittals will spook any fed prosecutor into dropping the same charges against others.
1A cases notoriously difficult to prosecute. All they'll do is plead First Amendment defense, freedom of assembly, freedom of expression, "I was just expressing myself." Very difficult to overcome the presumption of innocence in cases like this. It isn't an evidence issue, unless you mean lack of evidence. Remember, it only takes probable cause to arrest. That standard is far easier to meet than the "beyond a reasonable doubt" standard. Plus something like 90% (I think it's higher) of federal cases don't go to trial, they love to leverage plea deals. Let's just say a trial in federal district court is a somewhat rare thing.
Out of businesses in 7 years? Hrm what a coinky dink /s. That'll be 2025, when he formally leaves office.