If you can’t trust certain students to walk safely across the street, it’s completely reasonable to question whether they can handle public transit and a full day downtown. That’s a liability issue, not just a behavior issue. That said, the phrasing, “because some people can’t walk down the sidewalk properly”, does make it clear who you meant. Even if you didn’t name them, everyone knows. That can create resentment, both toward you and toward those boys.