Hijikata takes a few minutes to think about it. Harrison is such a hardass!! Why is the punishment so serious when Levi is an otherworlder and practically impossible to kill or permanently maim? (He sure is lucky that Harrison can't read his thoughts, and that Levi and Erwin couldn't either when the latter came to collect the former...)

Even though he could well afford to take the forced vacation - he has more than enough money in his bank account -, his pride simply can't take the hit of being temporarily suspended. So he opts for the paperwork, despite knowing that he'll go insane without the energy-burning patrols and the adrenaline rush of the occasional raid. For what it's worth, he's actually good at handling documents - he's thorough and efficient. He just doesn't enjoy it.

He does ask if he's still allowed to take time off to go questing. If that's still on the table, he'll just barely be able to balance things out! (That aside, genuine apologies are hard!! Can't he just make a cool heroic entrance whenever Levi next happens to be in trouble, and that'll cancel out the weasel shooting incident?)