Despite this, there's code for replacing the Masticator with Xander, but it is made unreachable with a dedicated code entry that makes Stuart Little disappear upon entering the 2nd street map if the Masticator is dead and the player is not yet a Prizefighter. There's also no code for replacement victory messages and the final one specifically mentions Masticator.
The following is based on unverified behind the scenes information and has not been confirmed by canon sources.
This suggests that Xander was deliberately cut before being fully finished rather than just unfinished or accidentally inaccessible due to a bug as some fans conjectured.
Mike the Masticator is based on Mike Tyson, and Xander that was to replace him - on his long-time rival Evander Holyfield. The developers probably thought that asking players to kill neutral boxers, an obviously evil act, to see bonus content was a bad idea and rather based the previous boxer on the roster, Evan Holyfeld, on Holyfield instead. This also allowed them to fully implement the ear joke (if talked to before the fight, Holyfeld mentions how Masticator has a habit of snacking on his opponents' ears, and he carries a proof on himself).
End of information based on unverified behind the scenes information.