Not that I necessarily support the ruling... but there was this in the new story:
"The Virginia Pilot reported high officials notified coaches by e-mailed prior to Wednesday's with reminders that the rule would be enforced."
So it looks like at least somebody in authority was told prior to the race. The coaches should have taken the steps necessary to make sure they were in compliance with the uniform requirements.
And I don't know if anyone here is familiar with the reasons that many schools districts are banning colored bracelets, but you might be interested to know that there are legitimate reasons for doing it.