Nobody trusts science, especially scientists.
I certainly trust science before I trust mumbo-jumbo.
Aikido is a system of budo relying on basic principles of psychology and physiology. Without those two elements, you Do have "a performance-based art" and not a functional budo.
Having crossed hands with Susan, I'd say she's got a good handle on the technique, art and science of budo. I can't say so much of many other alleged aikidoka with whom I've had the experience of training.
My teacher spent time in the dojo of both Shioda and Tohei and our jujutsu has a distinct and strong influence from the aikido of both of those gentlemen.
And having done budo for 35+ years (I stopped counting after 30, but IIRC, I started training in budo in 1973 or so) its been my experience that budo is both art and science, and it has naught all to do with mysticism or woo.
Good budo, that is. There's lots of stupid and ignorant and sadly uninformed budo out there, even in Japan.
Physically, if it cannot be described in terms of physics and other human science, it's non-existent.
Culturally, if it cannot be defined in terms of the vocabulary of art and human interaction, then it is simply woo and needs to be viewed as such.
Your mileage, it may vary, of course, but mine is fairly well calibrated.