You misunderstand. Inciting to violence is not protected, true enough. But Spencer's speech carries a subtext which clearly promotes violence. You perhaps think that discussing how to best exterminate a race is not advocating it, and that advocating it is not a tacit incitement? His speech is protected, but the 'reading between the lines' ideology is arguable, as I said.
Disagreed, although the poetic thing was pretty obviously tongue-in-cheek. For a lot of us, the law is not God, but more of a standard we have to answer to if caught breaking it. Do you mean to suggest that you have never failed to declare some cash income from a yard sale on your taxes, or come to a complete stop at a stop sign? We all knowingly break a law here and there, the question is only of degree. Spencer openly advocates taking legally protected rights away from others, and in doing so his philosophy entrenches him outside the laws as they are. It's at least a little poetic to meet him there on his own right-trampling terms.
Unless you made more money than the items cost, you would not declare it on taxes. You might be able to declare it as a loss for a tax reduction.