Living here in Japan in this day and age, I can tell you that Japanese practice both as a mixture every day. Most people have Shinto Weddings and Buddhist Funerals. It is quite interesting.
I also know that many of the Samurai class studied Zen Buddhism as a supplement to their warrior training. Also, there were some sects of Buddhist monks who were QUITE effective fighters when they needed to be. I agree with the author that not all Buddhists are pacifists. Not by a LONG shot.
Take care,
Ruck