It's a matter of professionalism and optics. I work for an impressively liberal financial institution, but I guarantee you I would be written up at best (probably fired) if I showed up to work in a pink schoolgirl dress and put a sign on my desk that said "Lolita's Credit Union."
The driver wasn't arrested. His identity doesn't appear to have been shared publicly. The wording in the article implies that he still works for the transportation company but was taken off of the school route. It's not like it's a witch hunt. He's just facing the natural consequence of unprofessional behavior.
If you're going to be the public face of a company, you shouldn't comport yourself in a way that anyone with half a brain cell would know is uncomfortable and offensive to your client (in this case, a Catholic private elementary school).