But the visibility, in this case, is aimed at making participation easier for shy kids who might hesitate to go to an assigned room to participate in a formal club activity. Doing this as an informal activity in a public place makes it easy for the hesitant to "sort of" participate, tentatively, hanging around the edges briefly, etc. It's often difficult for kids to join a new peer group in high school, even though many want to. Many fear rejection and some have actually been rejected when they tried. In a big public high school, many students who've been part of the mainstream school culture may imagine religious students to be very judgmental, and imagine that going to a formal group meeting would involve being lectured about sex, clothing, etc. or being pressured to participate in confessional type "sharing" discussions, or to declare religious commitment in a specific way.
I'm just not convinced that a dozen or even 2-3 dozen students standing around for a few minutes before school starts, in what must be the massive cafeteria of a 2200 student school, are being disruptive in any way, to "traffic" or anything else. And if they're not being disruptive, there's no need to push them into an assigned room. I'm just picturing the ordinary scenes around a large public high school shortly before classes begin, and the huge number of kids invariably roaming or hanging around in public areas, and I just can't picture how this group could be disruptive unless they were parked smack in the middle of a hallway and refusing to let people by, or praying at the top of their lungs to drown out normal conversation.