As a linguistics student, I don't like this argument. Orthographic <j> in English represents the affricate /dʒ/, which is unambiguously a phoneme in English. <J> by itself (generally) represents /dʒ/, so the <d> doesn't contribute any additional phonetic content to the word, so you could, in fact, call it a "silent" <d>. French has a phoneme /ʒ/, written <j>, but, lacking the affricate /dʒ/, has to represent that sound as a sequence of a /d/ and a /ʒ/, hence, <dj>. But when we're talking about an Anglicized name written and pronounced by English-speakers why should what French does be of any relevance?