Honestly, can't these kids just petition to join the IB program? What kind of HS blocks students permanently out of an IB program based on one 10th grade class? I can understand a parent having a beef with that kind of policy if that is the case.
We don't know enough about what this "cheating" consisted of. Did the kids work as a team on an assignment that wasn't a team project? If so, is much of the work at this HS or in this class normally team work? Is it a case of a study group whose members don't understand that working together to learn the material doesn't mean that they don't have to write it up individually? What kind of discussion did the teacher have with these students about the work, and how was it determined that their actions were in violation of school policy? Was this a first time event, or was it a repeat offense?
The article makes it look like the parent is out of his mind. However without the details of the case, we can't know for sure.