No you cannot, you have to withdraw by the deadline before the draft to maintain eligibility. I'm sure Oats himself told Grant he's not ready yet but could likely be more of a featured player for them next year and if he can continue to work on developing the 3 ball could get drafted. It was an easy decision now as he's likely making as much if not more in NIL now than he would overseas or if he ends up in the G-League or something. I believe only 1st round NBA draft picks have guaranteed contracts and he's not there yet.