While I get what you are saying, it's a fairly unreasonable worry.

"outlaws for life" in a western typefont is nothing like wearing something that says you are part of a biker gang.

Now if you had outlaws for life printed on the back of a shirt or jacket in the style of the gangs around their emblem then you might have something to worry about.

It's not the same as gang colors where someone can just be wearing a blue shirt in the wrong neighborhood and get killed. Bikers wear patches to represent their groups, no ones going to mistake a non biker based on a t-shirt for a game.

Also as I touched on, while their shirts/jackets may have writing on the fronts, they advertise their club on the back so you can see it while they are riding.