Sarah Boone nee Paulson, suitcase murderer, used her 'moment' to make a long and elaborate speech in court at the end of her case, victim blaming the victim and every member of his family and everyone she'd ever met by 'forgiving them'. It was so outrageous that only a true NPD could possibly consider it.
I think BK is the more seething silent 'superior' type and would not degrade himself to such low level antics (in his mind). I'm sure he's well aware that for the rest of his life, forensic psychology and psychiatry students will be interested in him and that people from all disciplines such as art therapists, social scientists, medical doctors, neurologists, psycho-pharmacologists etc as well as journalists, writers, general creeps, and murder fans will be fascinated by him. Sadly this is true and always the case. He knows this, he's been studying it. Many killers and murderers have been the fascination of the public and professionals. He doesn't have to make money out of it, he can however make a game out of it and I think playing (evil) games is the basis of what he did in the first place.
JMO MOO