If I may make 1 small point:
The media often uses lines/phrases like: "armed agents".
It is actually silly drama. Of course the agents are armed. They are law enforcement officers. When they conduct a search they come armed. They don't plan to execute a search warrant and say "oh let's not be safe today and carry our weapons because this person is probably just a reporter... who we just happen to be investigating in a gun case
As to the 1st amendment right part: If the Feds violated anyone's 1st Amendment Rights (or any other rights), shame on them... they should be punished/admonished/fined...whatever the courts find to be appropriate.
Of course, that is the truth. In the United States, law enforcement personel are always armed, so saying armed police is a bit redundant.
I can see how people might be suspicious that the raid was intended to intimidate Ms Hudsaon, rather than find Mr Flanagan's guns.
The article says that Mr Flanagan has a criminal record, but Mrs Hudson says that the agents tore her office apart more than any other room in the house and that agents did not take non-TSA-related documents from the office.
Maybe the officials involved in the raid only did what government officials do best, protect their turf.