The so-called assassin is a "Sovereign Citizen."  He's far right and he doesn't recognize the authority of the federal government but he presented no danger to Trump.

 
The sheriff went off half-cocked because he is a half-wit.  He has endorsed Trump for president:
http://www.nbclosangeles.com/news/local/riverside-county-sheriff-chad-bianco-support-trump/3427402/

 
He was also a delegate for Trump at the RNC (jump to the 2 minute mark):
http://www.youtube.com/watch?v=lU3tkZtP0BY

 
Today the sheriff was interviewed from his home.  Right behind him on the wall was a big cross.
What happened to that man was a preview of what law enforcement will be like if Trump wins.  Onward Christian cops doing whatever Trump tells them to do, the Constitution be damned.

What assassin tells the cops “hey just to let you know I have firearms in my car”  ?

This guy is going to sue the authorities for releasing his name and photo to the press.  If the police had probable cause, no rights were violated, and unless sealed by the court, arrest records are public information that can be accessed by the public on request, sometimes informally, and other times through an FOIA request.