Sidwell Friends did apologize for the Pearl Harbor Day menu.
At that link there was another link to the apology, though I didn’t watch it.
I never have heard of “Society of Friends”, myself and remain curious about the connection between the name Friends and its use in other institutions like the Sidwell School, and the Seminary.
You asked who are the “Society of Friends.”
They is another name for the Quakers. Sidwell Friends is a Quaker school founded in 1883.
en.wikipedia.org/wiki/Quakers