If the claim is true whatever action was necessary would have been taken, I am sure, to ensure that the Germans were not aware that Enigma material had been seized at Dieppe, even if that meant not using the seized material for a period of time. In the event the commandos didn't manage to seize Enigma material at Dieppe.
I am neither going to dismiss nor confirm the claim that an attempt was made to seize Enigma material at Dieppe,because I wasn't there, but I can see how it could have been done in a way not obvious to the Germans.