It is quite on the cards, that the reason why the Prisoner resigned was of secondary importance to the Village administration. It wasn't the reason why the Prisoner resigned that eventually saw him abducted to the Village, it was the act of resigning that did that.
Few No.2's were charged with obtaining the reason behind No.6 resignignation, and finally when No.2 did actually obtain that information, it didn't seem to matter. No.6, in 'Once Upon A Time,' told No.2 why he resigned. "For peace of mind. Becasue too mnay people know too much, I know too much about you!" he told No.2. But apparently No.2 wasn't listening, because he asked No.6 to tell him again, but No.6 wsn't one for reapeating himself, "You've been told."
I wonder if the reason why the Prisoner resigned was simply a quest for information, to make up the Priosners personal file, after all No.2 od 'Arrival' told the Prisoner that they like to know everything, and the Prisoners persoanl file would be missing the reason why he resigned, as it was supposedly missing the Prisoner time of birth, althoiugh that was deliberate. No.2 thought that if the Prisone would give the time of his birth, that all the rest would follow, he was wrong, and his predecessor during 'The Chimes of Big Ben' was also wrong!
Be seeing you