These are people who do the work of a Teamster, but invest in the communities they visit simply to improve and reunite the fractured communities they visit. To them, it is their mission to ensure that travelers are safe, and this may include bumping off raiders or troublesome Outlaws. This is occasionally an unpopular action, but the general culture of Teamsters ends up a bit more self-governing because of it.
Cowboy in Teamster culture starts to be said as a compliment, or a backhanded version of "you mean well but you're crazy." True Cowboys know each other, and may band together for risky actions.
Some elements of Cowboy culture resent Rebel, preferring to empower people to seek their own future rather than try to force them to mimic The Teamsters' Rebellion. They lean more Libertarian, often critical of power but with a laissez-faire approach to overturning it. So the Cowboys are effective police of behavior when they target bad Outlaws, but in regards to the power structures of communities they visit they often side conservatively, citing self-rule as the right of the locals.
But they're no stranger to minor Outlaw actions, often skirting the rules and boundaries they don't agree with to get by. Cowboy can sometimes be used as a synonym for "Daredevil."