The Supreme Court meant the disruption-standard for on-campus speech.

If they let schools punish students for off-campus speech, on the grounds that students later talked to each other in class about the subject instead of paying attention in class, then they can punish students for:

a) Exposes of wrongdoing by school officials
b) Criticism of the US president

Students should be able to write criticism of school officials and other government officials without being punished.