Who cares if it was spur of the moment? The deadline is tomorrow. He could have pulled out at any point in between when he declared and now, and he hasn't. That, coupled with the fact that he worked out for a team today, suggests (and I emphasize "suggests") that he staying in the draft.
People can point to other factors, but the fact that he ostensibly received tepid feedback and still has withdrawn is a pretty good indication of where he's leaning, regardless of what some might like to believe.