What does Rowdy really mean when he calls Junior "nomadic'?

Rowdy is referring to the fact that Arnold left the reservation for school..... that he had found a away out.

"I'm not nomadic," Rowdy said. "Hardly anybody on this rez is nomadic. Except for you. You're the nomadic one."

"Whatever."

"No, I'm serious. I always knew you were going to leave. I always knew you were going to leave us behind and travel the world."