I don't really know the why, other than its use appears fairly normal for a person (anon) that is experienced working in an environment where the Dutch language is used. The words used aren't out-of-place or stilted. Perhaps the Dutch originated with that person's Twitter or browser. It could also have been the anon's notes to himself or herself.
Educated Dutch people pride themselves on being chameleons to a target language, so why this anon didn't take the easy and more impressive route to use English seems a just a little stubborn.
I imagine the Q-Team wished to preserve the anon's work rather than edit it.
RR’s father called him that.