Why does Mr. Underwood feel that Tom Robinson's death is a senseless slaughter?

In his editorial Mr. Underwood calls Tom's death a "senseless slaughter of a songbird"; this of course ties directly into the title of the novel. Tom is an innocent mockingbird killed by ignorance, injustice and bigotry. Mr. Underwood is a man who lives by his own rules. Printing this, however, puts his business and himself in jeopardy. Mr. Underwood feels very strongly about this travesty of justice.

In his editorial Mr. Underwood calls Tom's death a "senseless slaughter of a songbird"; this of course ties directly into the title of the novel. Tom is an innocent mockingbird killed by ignorance, injustice and bigotry. Mr. Underwood is a man who lives by his own rules. Printing this, however, puts his business and himself in jeopardy. Mr. Underwood feels very strongly about this travesty of justice.