That's silly
They wanted a particular person out of office, and were showing what would happen otherwise.
It was certainly not a mayhem attempt, since for that you have to articulate the terms of the contract for it to work.
It may very well have been an attempt to affect the election, but terrorism is a blunt instrument. Sometimes it moves opinion against those whose job it was to prevent the attacks, or those whose policies may have invited the attacks. Sometimes it enables a mediocre president to hang onto office longer than otherwise.