The letter should have read” Arm yourselves and meet in the lobby to repel boarders.”
People should be able to protect their property from savages. It was legal during the Indian wars in the west and should be legal now.
People do not buy property to abandon it when it is threatened by ignorant rioters.
They are free to stay, but they may not be able to leave. If it was my place, I'd stay for the weekend.