C.O.
Rosebud:
It could mean several things - that he hasn't posted anything lately. Or that he has his privacy settings set soo high - and this does happen - that even though you are a friend, you can't post on his wall - one my friend's had this because his soon to be ex wife was going psycho on his wall. We could comment on his posts and pics, but we couldn't go to his wall and say "HEY!!"
Send him a message and ask him if he has his privacy settings set too high that you can't post on his wall. If he does - like you said - you don't want to be friends with him then!