That question is nonsensical: 1. The jury never has to justify anything; 2. "Murder" is a legislated concept. The jury is not beholden to the legislature, and is constitutionally empowered to reject the laws they create. They do have to follow the law, but the law includes the constitution that demands and empowers them to make their decision as laypersons.

Where the jury feels that enforcing the legislated law would be an injustice, they are free to rule "not guilty", even if they believe the accused's actions violate that law.

To more directly answer your question, though: If the jury felt that the healthcare extortion industry was completely out of control and a clear and present danger to society in general, they could determine that the legislated prohibition against killing did not contemplate this particular killing. They could determine that the accused does not deserve to be convicted just because the legislature was shortsighted in the way they wrote the law. I'm not saying the law is actually shortsighted, nor am I saying that the jury should nullify. I'm saying that they could "uphold the law as written" and elect to acquit him under the authority conveyed to them, in the "written law" of the 6th amendment.