One of the definitions of "science" at Dictionary.com is the "systematic knowledge of the physical or material world gained through observation and experimentation".
To many of us, explaining taiji in terms of science is to use what we know of modern science (usually physics, biology, those things we learnt in school) to explain what we learn/experience in taiji. Given the success of modern science in explaining physical phenomenon (and its pervasiveness in our education system), this seems like the correct way to do things.
One small problem, though. Taiji was created (conceptualised, documented, passed down) using a system that isn't based on modern science. So trying to explain taiji in terms of modern science is like trying to explain the monetary system based on mechanics. It may help the physicist to understand the monetary system a bit better (because you are talking his language) but it cannot fully explain everything. To better understand the monetary system, it may be better to learn a new "language" called economics.
So what is this "language" when we need to talk about taiji?
I think it is the system of classical Chinese philosophy and medicine, which was what taiji was explained using back in the past. Yin-yang, the five elements, acupoints/meridians, these are the concepts behind taiji in the past. To truly understand taiji, I think we need to understand the "language" behind it.
And is using this "language" a scientific approach to explaining taiji? Well, it is the Chinese system of expressing "systematic knowledge of the physical or material world gained through observation and experimentation". (I am not so sure about the experimentation part as we understand experimentation methods today, but I am quite sure there was a lot of trial-and-error that went into this "language".) I would dare say that it is the Chinese system for science, and a widespread system too, being used in East Asia for a few thousand years (before modern science appeared in the last couple of hundreds).
So while we may want to understand taiji using a "language" familiar to us (aka modern science), maybe it is better to try and understand taiji using the "language" it was created in. Learning a new "language" is not easy, but I think the effort will pay off in helping us to better understand taiji.