Stupid, inconsistent, decision on Blizzard’s part.
Edit: So I wanted to add to this because the above, my original message, is not really good feedback. I did make a full feedback thread on this subject over here for anyone who wants a hefty read but ill summarize here as well.
So I say this is inconsistent because there are several other legendaries that this same restriction “could” be argued that they should be applied but are not. As people have also pointed out, you can do the DH transmog unlock on non-dh characters as well so its not even required to be a DH to unlock this DH exclusive feature.
There is honestly just a whole lot wrong with this choice in my opinion that continues to show Blizzard’s inconsistency with design choice. I go pretty in dept with thread on the Warglaives situation and also did one with the Long Boi and covering the inconsistencies with that situation also.