This has nothing to do with Bush - there was a guy on Kuro5hin back in the Clinton days (I think) who made several comments regarding the best way to attack the presidency - such as through the vice president. More information
here.
This is not "omg bush scare tactics" - this is the Secret Service doing their job. Anyone who is brought to their attention who threatens the Presidency is investigated. If you do a bad job at work, your company may lose money, or you might get fired, or you might set the project back a week or two. If they do a bad job at work, people die.