Did he report it to the authorities?
No. I suppose he forgot to mention it to them.
No.
I suppose that depends on whether he was there- before he wasn't there.
In this case, it is probably true that he voted against action and resigned. But methinks first and foremost in his mind was not so much the safety of US officials, but the fact that he had his eye on a Congressional seat the following year, and this would "go down bad for him and his career." So he bailed out.
But several questions: Why lie about having been there, and secondly, why did he not assist the police and Secret Service in breaking up the actions of the more radical faction? Disturbing.