From what I've seen of 'ninja' training it is not geared towards any kind of competition.
The art I train is totally focused on self preservation. My sensei routinely states the fact that we would get owned in competitions: Point sparring, mma, kendo etc. We'd be hamburger.
Double checking our web page we don't discuss competition training. We routinely get phone calls asking about that, which are redirected to the BJJ group and a few other schools who do compete.
However, we do not state that we are simply just too dangerous for competition.... That is a crock.
Spanky