> ... is it actually 'music', by any definition?

Well, if you take the purely academic definition of music as any
organization of sound, or lack thereof, then certainly, yes, though
whether it is a pleasing music is a matter of personal preference.

One of the fellows in my music history class just this afternoon
remarked that some of the Stravinsky pieces we had been listening to
were too grating for his taste, and his atonality was mild compared
to many other composers.  The Disklavier performance is definitely
intriguing as an exercise, both in the idiom and of the capabilities
of the instrument, but I personally wouldn't want to attend a concert
of such exercises.

Then again, there are those who might.

Ben Willis