Personally I have no doubt it’s a safety concern.
POTUS just spoke to the press rope line, about various topics, and was asked about this cancellation.
He said it’s because of the DC Mayor having DC shut down....he said (paraphrasing), ‘rules and regulations....DC is shut down....we have a hotel, and, I guess you’re not allowed to use your hotel...because everything is shut down. Can you imagine? DC is shut down’.