No.
I personally don’t know if the student could regulate his behaviors given changes to an international itinerary.
Lots of people in airports and their behaviors could trigger any behaviors for the child including: movements, conversations, airliner announcements, unfamiliar staff.
Flight delays, lost luggage, overbooked flights, overhead bin issues, unfamiliar smells and scents, etc. may cause problems; we just don’t know what will trigger some behavioral issues.
I would feel for the child because it’s really not their fault that certain things may trigger the anxiety.
I am hoping all goes well but you just never know that’s why I would just say no. I’m happy that the parents are supportive of their child but we just don’t know.
Edited to add: the parents need to go on the trip as chaperones because as parents, they tend to know which parent can keep the student calm with certain feedback.