Read the bold in each paragraph as if it was one sentence. That is the purpose of the law. It's saying you can't destroy government property or assassinate government officials. And it is certainly very Constitutional. We are by no means allowed to kill people just because they work for the government, or wreak destruction on property.
So tell me, if the government becomes so corrupt and out of control (and I am not claiming that it is or is not the case now) and it is obvious that the government needs to be replaced, and they simply say NO to peaceful means for the people to take back their country, what are the peoples' options then? By the government merely passing a law stating that it is against the law to remove them, does that neuter all Constitutionally valid means to remove them if they refuse to go willingly? The US Constitution wasn't designed to protect the government from the people, it was designed to protect the people from the government it was creating. Our forefathers KNEW they were creating a potential monster. Read the Constitution with this in mind.
In the phrase "all enemies, foreign and domestic" what defines a "domestic enemy"?
The government would be dismantled anyway, so what would it matter? Whoever is leading the Revolution would have to make the new rules.