In his own way, Gerald Tetley is as responsible for Croft's inaction as his father is because Gerald reveals a very important truth to Croft: Men are usually greedy for power; this power is not the only impulse in the human heart, but it is a strong force. It is the existence of this drive for power that necessitates his heeding Davies's arguments about justice. If men are not careful to remain within their social and ethical boundaries, the powerful impulses Gerald describes will take control.
Unfortunately, Gerald's person impedes his message. He is slightly built and more pretty than handsome. He lacks the confidence and will of his father. He is, in the judgment of these cowboys, effeminate and weak. In addition, he is young and his ideas are bitter. If he were more "normal" in his conversation with Croft, he might have better luck but Croft will not listen to a girlish cynical boy about such a weighty matter.
Finally, though Gerald proves that he is a man of integrity in spite of his many weaknesses. He promises to kill himself if the lynching occurs and he does. This is courage but not the kind of courage needed in this case. Gerald can correctly diagnose the disease in Bridger's Wells, but like Art, Gil and Rose, his response is to find an escape rather than to effect a cure.