Just because the organisation uses open-source software doesn't excuse them from public and professional scrutiny.
An MP spending £1645 on a duck house under expenses got a lot more attention than this little bit of waste. Just redressing the balance.
Efficiency is a major problem in government. Government should have a low financial impact on society where possible. A government entering a market with an already solved problem is wasteful at best. If they'd contributed time to Nginx or mod_proxy then they would have a net positive social effect.
But they didn't. They built an inferior product at great cost to the taxpayer.
Is this some sort of Markov-chained free-market/El-Reg-at-its-most-prolix/libertarian experiment in satire? Well played!