You ask “What should we do- sit solemnly and gravely nod in a restrained way when the kid gets his diploma?”
Yes.
And we should avoid colorful, loud, or boastful clothing as well. Grey, black, and white are appropriate.
The band should play only the National Anthem, and no chorus or other music.
People may applaud quietly but only for so long as the Administration does, and no longer.
Smiling or other outrageous displays will be dealt with.