Why is it that Leviathan's items remain useless? (GC turn-ins/desynth)

[Histoire]

I imagine those should be available for the aforementioned in 2.51 alongside Armoire updates for the recent (seasonal)events, or at least I'm hoping.

[Atomnium]

That's a very good question, in fact I had to toss some Leviathan weapons 2 days ago, nothing else to do with them since long :x