I'm not sure. I have no use for the guy, but if it's a credible threat, he should get protection. I thought the Capitol Police handle security for Senators & Congresscritters, not the USSS. Maybe it depends on the seriousness of the threat.
Could it be some Jihadies looking to punish an apostate as proscribed in the Koran?
Jihadists would be the most likely logical candidates for threats on B. Hussein Obama. Pehaps in this day and age all major candidates should be provided some level of protection if their own private security personnel can not handle it. My guess is the jihadis would like nothing better than to disrupt our national elections.