What is astounding is that allegedly patriotic and civic minded Americans see this as so unreasonable. There isn't so much as a hint of any wrongdoing on the part of the civil servants; they just asked him to show up as required by law.
You might not like the IRS, and think that they have been unfairly taking your hard earned money. Does that mean you can call them up and say '(explative) you, I'm not paying my taxes, bitch'. No, you can't. You could make as many ad hominem attacks against IRS agents you like, but you'd be on the wrong side of the law.