Earlier quoted context omitted.
I don't believe there are any laws against shooting federal agents actually, though I could well be wrong, but in the absence of a verifiable warrant, there's no guarantee that they are federal agents. Even if they are federal agents, that doesn't give them any right to enter your home without your consent, absent a warrant. I don't otherwise disagree with the synopsis you've put forth, I'm just saying that our right…
http://www.law.cornell.edu/uscode/text/18/1114 Fun fact: Timothy McVeigh was convicted of the murder of 8 federal agents who were in the Federal Building. They didn't bother to charge him with the other 160 counts of murder, because those weren't federal crimes.
If I kill someone attacking me, I have committed homicide, but not necessarily murder. If I kill someone ala McVeigh, I have murdered them.
Since it is a federal charge, it's very likely that the 'intent' would be determined in a federal court, which does exist outside of state jurisdiction and is bound to uphold federal laws, but it isn't quite open and shut.
Still, your point stands, which is to say that he's almost certainly screwed.