What did Bryon mean when he asked himself, "Was Mark a throwback?"

In Chapter 10, Bryon comes home and is emotionally drained. He looks for a cigarette to smoke because he is stressed out about the traumatic events he's recently experienced in life. Bryon does not have any cigarettes in his pocket and remembers that Mark has a spare carton under his mattress. Bryon reaches under the mattress and pulls out a long, cylindrical tube full of pills. Bryon then realizes that Mark has been selling pills and calls the cops on him. When Mark walks in and sees that Bryon has found his pill stash, Mark tries to explain himself by saying that they really needed the money. While Mark is talking, Bryon begins to think of Mark's "golden-eyed cowboy" father, and wonders if Mark was a "throwback." Mark has absolutely no concept of what is right and wrong. He doesn't obey any laws because, in his mind, there are no laws. Essentially, Mark is a modern day cowboy who lives by his own rules and doesn't care about authority. Bryon recognizes Mark's "cowboy-like" approach to life, and views him as a "throwback" version of a Wild West Outlaw. Bryon believes that Mark needs to learn that he cannot do whatever he wants without paying the consequences which is why he calls the police.