Can tell you now, if you'd like. It looks like it was a micro-optimisation for the case where we need to render a 410 from `rules.rb` (see https://github.com/alphagov/bouncer/commit/e0d52a855eb19483ea767511181f31349fce2fa1 / `rules.rb`). Without it, you have to instantiate another request object in that one case.