To me it doesn't bode well for the script if he would rather have League of Extraordinary Gentleman as his last film than this. Especially if his part wasn't that big. He wasn't even supposed to be in the actual adventure, meaning little, if any, actual action scenes. Sure, he has to be on set and there is the preparation, but how long could he possibly be shooting for? A couple weeks? It doesn't look good.
Unless, as deckard24 mentioned, it's a big cover and he does actually have a cameo in the film, but I REALLY doubt that would happen.