That sounds a bit snarky; it just seems like purity/impurity is the favorite bikeshed for haskell programmers.
Sometimes people like to write about their pleasant experience before the project is completely finished. I'm bookmarking the project as a good example of Cabal Project structuring and use of some network libraries. Good examples like these aren't very well curated from the universal Haskell repertoire.
Since it's an internal effort, simplicity trumps security and features. I doubt making the IRC server more complete would be worth the effort and maintenance cost. It's much better to add features only of they are obviously missing when they actually use the server.
https://github.com/chrisdone/hulk/commit/d9093c76a49ea417091...
It's his project, he calls the shots. If you want a feature, get in and write it. Being Right On The Internet doesn't mean shit.