"The German Army is the perfectly adapted, perfectly running Machine. The difference is that the Germans are organised with a view to War...with the cold, hard, practical and business-like purpose of winning victories."
G.W. Steevens - The Daily Mail (1897)
Maybe it had to with the fact that Rogge was awarded the diamonds version of the Hilfskreuzer badge and wanted to show this?
Since the special diamonds versions of the various Kriegsmarine war badges were never officially instituted and thus not included in the 1957 range of awards, he would not have been able to get a replacement badge with diamonds, only the standard pattern.
(Of course, it was still prohibited to wear the version with the Swastika no matter what, but apparently he got away with it.)