Injun wasn't going to let Dorgan put him out.
At this moment Whitey arrived.

What would have happened to an unarmed boy against a drunken, armed man or to two unarmed boys, for Whitey started to interfere, is something else we never shall know, for a cowboy put in his oar.
You know that a cowboy remains a "boy" until he is old enough to die.
This one was sixty, he wasn't a typical puncher at all.

He had a thin, hawk-like face, steady gray eyes, rather long hair which also was gray like his moustache and goatee.

He had been a soldier and an Indian fighter, and he looked it.

As Dorgan lurched toward the boys, who stood tense, with flashing eyes, and prepared for resistance, this cowboy stepped between, and spoke to Dorgan.
"I wouldn't do that if I was you," he said, and he spoke in a sort of drawl, but there didn't seem to be any drawl in his cool, gray eyes.