Basically, the FBI would be able to take away someone's constitutional rights by simply placing them on a list, without having been convicted or even charged with anything.
You mean just like the IRS does to conservatives and Tea Party groups?
It will stand up in Court after November if Trump does not become President. The USSC will quickly become 6-3 Communist and the lower courts already have a whole string of cases waiting to go to the SC that will negate most of the Bill of Rights.