This was also said in the same thread.
"Good to keep it quiet so as not to have another recruit misconstrue the commitment. This kid seems willing to play the 6th man role. Don’t need a potential starter questioning his place."
Even if Stojakovic doesn't go to UK, they'll get another highly recruited wing to battle Saunders for playing time.
If he already told people he was coming, he would have signed by now. I can't think of a logical reason to wait.