Nishiyama-sensei passed away nearly 10 years ago. I had the chance to meet him when his organization held their Canadian national championships in our town, we did a kendo demonstration at his request. He was a very gracious and interesting fellow.
No opinion on his interpretation of "shihan". In kendo, we use "hanshi", which means exemplary or model person, i.e. someone to look to as an example for your whole life, not just martial arts.