[mild spoilers for jørgen + klaus routes]
Oddly enough in jørgen route you can find Klaus messing around with some project in the empty art exhibition hall, so the devs may have some of the script for his day 3 done already.
My guess is that since his route is parallel to the others (like Klaus' wooden hut scene being parallel to the game night) it makes sense to update his route when the others' are already out.
Hopefully we get an update when more characters get day 3