Although it's a useful example, it doesn't necessarily show an advantage of Perl over Java -- it shows an advantage of modifying an existing system, as opposed to restarting from scratch.

Depending on the exact details, it could also show that bringing in programmers who aren't familiar with the underlying business processes can hurt the development of new systems -- sometimes (most times?), it's better to take the time to training current employees in new technologies, than to bring in a contractor or outsource it.

(and I say that, currently doing long term contract work ... and I still don't understand most of the data that I deal with, 3 versions and 18 months later)