German success with Purple - Part 2

Part 1 is here.Looking around I found a report that has an interesting response from a high ranking German official.

From TICOM I-200  ‘’INTERROGATION OF MIN. RAT. WILHELM FENNER OF OKW/CHI’’:

FIFTH INTERROGATION  2/10/46

39.Japanese Machine.

FENNER was asked whether he could describe their work with the Japanese "Schiebe" . He appeared genuinely surprised and said that he had never heard of it; nor did he recognize the indicators CIFOL VEVAZ. When told that HUETTENHAIN had spoken of the solution of this machine, he said that surely there must have been a misunderstanding, and HUETTENHAIN must have been speaking of the diplomatic transposition cypher. He firmly denied all knowledge of the existence of such a machine, let alone the solution.

Wilhelm Fenner was a Principal Specialist , Chief at Division B of OKW/Chi (Cryptanalysis)

Fenner’s response is strange to say the least.In 1938 OKW/Chi had cooperated with Pers Z in the solution of the Japanese RED cipher machine.This was solved and the traffic from Sept ’38 to Febr ’39 was read currently.Then the Japanese replaced that machine with PURPLE.So why would he keep this a secret from the Allies? Surely the solution of that cipher was important back in 1939 but in 1945 there was no reason to deny it.Or is there ?

Was Fenner surprised because he thought the interrogators were referring to the Purple machine ? Why would he want to mislead them if the Germans had no success with it ?