The others reach the remains of the statue, Richard reveals it's where Jacob lives

Back with on Locke's trek to Jacob, Richard and the group come to a stop causing Locke to ask why they are stopping. Richard just says "you'll see" as they step forward and the remains of the four-toed statue come into view.

Locke says "Well, it's a wonderful foot, Richard, but what does it have to do with Jacob?" Richard says "It's where he lives." Locke looks a bit sinister and menacing as the start to move closer.

If we assume that fake Locke is the man wearing the black tunic in the opening scene of the finale, how is it that he didn't seem to know where Jacob was living? Is he unaware of where Jacob has been living since he left the cabin? Locke seemed a bit pissed when he found out where Jacob was living.