so is aiki jujutsu an oxymoron?
Well, the specialized physical strengths of "internal strength" have to do with harnessing the groundpath strength and the weight strength (Earth and Heaven) and manipulating them in the body (Man), but that would be one topic, the specialized strengths. Manipulating the specialized strengths in relation to an opponent's incoming force so that the two forces result in the attacker's force being negated, that's "aiki". What the Chinese refer to as Hua-jin ("neutralizing jin") or other names. Since all the styles use different names for the basic forces it can get confusing.
So "jujutsu" could just be the "techniques using internal strength", but "aiki jujutsu" would be "techniques using internal strength that blend with an opponent's forces and neutralize his attack" (opponent defeats himself). A good interview with Minoru Inaba translates this as "shut down your opponent's power", but I think it's more because the interpretter didn't fully understand what was meant (same idea, though):
(about 2/3 way down)