Nightfighter,
Welcome to The Firing Line! Glad to have you.
The arts you study are more correctly called kobudo, not ninjutsu. Of the nine Ryu, only 3 (IIRC) are, in fact, deemed ninjutsu lineages, with Togakure Ryu being the most famous. (Hatsumi is, of course, really making his own school as well, so that would make 10.)
As has already been intimated, there is a lot of misunderstanding of what "ninjutsu" was. There are tactics in dedicated "Samurai" schools that were called ninjutsu as well (to encompass such items as night work, b&e, and small unit tactics). Many ideas about ninja derive from Japanese fiction and theater, including the black suit ("shinobi shozoku") .
So, in summation, the arts you study are more just traditional Japanese battlefield arts. We in the US have actually seen very little of the "ninja" schools, even in the "x-kans" (Bujinkan, Jinenkan, Genbukan). You will give yourself more credence- and, in fact, be more correct- if you just drop mentioning ninja, ninjutsu, or (perhaps) even ninpo when you describe what you study.
I must say I take some umbrage to even mentioning kobudo being taught to SMU's (Special Forces, Force Recon, SAS, etc). There are several reasons for this. For one thing, individuals members of Special Military Units can take whatever instruction they want, and the teacher who taught them can then claim to have taught Seals, or whatever. Big deal. Secondly, the very nature of these arts makes them unsuited for quick integration into a modern fighting unit's repertoire. Waiting for that sword strike from behind is not really something Joe Grunt, Snakeater Extraordinaire, really has time to train for.
Folk like Skorzeny are, I believe, put off by two things. The most obvious is the poor quality of some senior American Bujinkan instructors. (I will admit I started training under Stephen Hayes. I was quite happy when my initial six months were up, and I could move on; I could already tell I wasn't getting "the real deal". Before I move on, let me say something nice about Steve: his wife is great- and very dangerous- and his kids, when I knew them, were absolutely super.) I have seen a Bujinkan "10th dan" (the same one who offers the black belt by video course) who could not fight his way out of a paper bag. It would be very amusing to pit Skorzeny against him; in unarmed combat, I'd give 4 to 1 odds on Skorzeny without hesitation. The second, and not quite so obvious problem some martial artists have, is the debatable history of the lineages that compose the curriculum. There is an easy way to handle this. (I'm quoting, here.) Shut up and train. You can tell when someone is genuinely dangerous, by how they move. If you're not with someone in person, you'll never know, regardless of how well they "talk the talk".
Ninpo ikkan!
John