In what way is Mr. Underwood's editorial in the Maycomb Tribune similar to Atticus's advice to Jem and Scout when they got their guns?

I think the basic theme is that Tom Robinson was an innocent. He was like a Mockingbird who was killed because of bigotry rather than breaking any laws. Atticus explained that Jem should never aim his gun at a Mockingbird because all they do is bring joy. Tom is very similar in that way.