Just because he is a member of Starfleet dosent mean WE the players have the required clearance to be told where he is.
Sure, we may even be of equal rank by endgame but Starfleet should'nt be giving out such information when they have the potential for spies and Undine Infiltrators. You get told what you need to know and no more.
Thus, the option to play 'where's sulu' is valid via rumours and obscure means. Of course, I imagine Sulu will become unhappy at being 'stalked'.
Then again, I imagine this could make a good leadup for more incidents involving Section 31. They are bound to be impressed with a player that is so capable of finding an elusive target... they might even suspect your an enemy agent and conduct the proper tests.