I do like your theory, however, I must correct you. As far as I am concerned, the SO6P's creation of all things is done by combining yin and yang. In other words you create something spiritual, and give it a physical shape. This is by any means not comparable to what Tsunade (and presumably Mito) can do.
Kishi is rather keen on details, when it comes down to scientific stuff. I think you do understand her technique, but simply misunderstood, what the sage was able to do. Most think that because he created the 9 tailed beasts, he could create life itself? That is a rather optimistic belief, and by any means completely incomparable to, what Tsunade can do.
The 9 beasts are created from something, that was already composed of enormous chakra. One could even say that the 9 beasts are actually chakra from the juubi, but split by the spiritual form, that the sage placed inside them. Beside of this sole example, I don't believe he could create life itself. It's simply senseless, and he would never have died, if he could do so. Creating something spiritual and placing it inside a shell, which is capable of creating chakra from nature itself, is very different from that.