Does the disagreement of Abu Bakra and his companions concerning the ruling affect the obligation of the hadd?

Primary text

The disagreement raised by Abu Bakra and his companions was not regarding the obligation of the hadd upon them if the testimony was incomplete. Rather, their disagreement pertained to the validity of what they had testified. Since the slanderer did not bring four witnesses, the hadd is obligatory upon him, just as it would be obligatory if he had not brought any witness at all.