You got the trophy if you posted in this thread
during the 24 hour period it was open. Was a fun little thread since you didn't even know you'd get a trophy until the end lol. It was an attempt to be a very similar thing to the Breakable Brick trophy
, with it being an exclusive one time thing.
But just to clarify why
it isn't darkened out even though you can't earn it anymore: I generally leave "new" trophies undarkened if the event was "recent", as in the last few months or so. Otherwise a lot of trophies would go straight onto that page darkened out (see things like this C3's recent trophies aren't obtainable any more, but very recent) which would be a shame.
But anyway, it's probs due to be darkened out around now anyway so... it is now!