Is anticipation of a rebuke a "prebuke"?
It's paradoxical, but to keep the Zone a bucolic place, one must be restrained in one's use of rebukes, and not become a bukaholic. One must also be willing to retract a mistaken rebuke by issuing a debuke. And in this case Jacob's unnecessary prebuke requires issuance of a deprebuke to balance the bukes...er, books.
Or something like that.