BC is not so odd a choice when one considers he is heir apparent to Ky Bowman who is a likely to be drafted by an NBA team this week.
Perhaps likely isn't the right word. For example, Shamorie is listed by ESPN as the 46th best overall and 4th best point guard in the draft, while Bowman 70th and 11th, respectively. Meaning that if Thornton had come to St John's, he would be an heir apparent to a player who is likely to be drafted, as opposed to Bowman, who is unlikely to be drafted.