If one is to do a thorough analysis of the names, the easiest solution is clearly Bowser.
Chargin' Chuck has already been used before so the bomber might have placed it there in hopes of someone making the same choice, clearly attempting to bait someone into a false sense of security. Obvious play.
Then of course there is the Goomba, who seems so simple and innocent of a pick that no one would think twice about a bomb being placed there. It's highly likely it is here that the explosive has been planted, based off of such evidence.
The character of Bowser is one that you may expect to have a bomb, and that is precisely what the bomber hopes for; by using Bowser's personality to trick players, he is subtly pushing them towards the other two words, which have been established as easy candidates for holding the explosive.