If no maintenance was carried out during the stop, the normal control check for freedom of movement could be safely assumed to also be a check for correct movement.
It's interesting that the initial report says that there was no evidence of a control check prior to takeoff. That would mean that if there was some restriction to free movement of the elevator, that would only have become apparent at some time during the takeoff.
That said, though, I doubt that the control column should remain fully or almost fully forward during the takeoff roll, where it would be with the aircraft stationary with the controls locked. You would expect it to sort of "float" backwards to a neutral position in response to air loads, the column position corresponding to the elevator position, ready for the nose-up input associated with the "Rotate" call at VR. Not seeing the column move in that way should have triggered some sort of response from the crew, so that a working assumption would be that the control column did move aft in the normal way. This logic I am using argues that the controls were not locked.
This is still a puzzling accident, so that it will be very interesting to read the final report, but reading that there's no evidence of a control check seems to be one piece falling into place.