The main joke is that it’s a ridiculously over-the top response to a very trivial achievement.
The misquote of substituting “Jesus wept” for “Alexander wept” just adds to the absurdity.
Both the Alexander quote and the biblical verse are quiet responses to events of great significance. This contrasts to the dean’s minor achievement of… increasing a font size.
The fact that “Jesus wept” is sometimes used as a mild expletive just serves to make the quote more annoying to the other characters, which adds to the joke.
There is another layer of reference that is almost certainly deliberate: in “The Lawnmower Man”, the name Jesus is used a lot as an expletive. As the titular character’s power grows, he declares himself to be a god, and ultimately (in a memorably cheesy line) “CyberChrist”. Anyone who has seen that particularly daft movie will appreciate the reference.