In his editorial, Mr.Underwood concluded that?

Mr. Underwood concluded that Tom Robinson's death was senseless. 

"Mr. Underwood didn't talk about miscarriages of justice, he was writing so children could understand. Mr. Underwood simply figured it was a sin to kill cripples, be they standing, sitting, or escaping. He likened Tom's death to the senseless slaughter of songbirds by hunters and children, and Maycomb thought he was trying to write an editorial poetical enough to be reprinted in The Montgomery Advertiser.

How could this be so, I wondered, as I read Mr. Underwood's editorial. Senseless killing-Tom had been given due process of law to the day of his death; he had been tried openly and convicted by twelve good men and true; my father had fought for him all the way. Then Mr. Underwood's meaning became clear: Atticus had used every tool available to free men to save Tom Robinson, but in the secret courts of men's hearts Atticus had no case. Tom was a dead man the minute Mayella Ewell opened her mouth and screamed."