I would define music as an organization of sounds that may shift in pitch, tone, or timbre and that are produced in a manner dictated by some rhythm or tempo. This is left very vague and broad to fit in the entire range of music from Gregorian chant to African drum circles to Einsturzende Neubauten, who made songs hitting corrugated metal with hammers, to John Cage's 4'33", which I would consider performance art but which some would consider music due to the fact that it has sheet music and that tempo is essential to its performance. In this framework, dubstep is undeniably music. Modern music has done away with many of the more rigid rules of classical music theory as well as introducing ideas that 18th century composers couldn't even consider, so dubstep may be unfamiliar or incomprehensible to the ears of some, but it cannot be justly denied that dubstep is music.
That said, all I've ever really heard of dubstep is Skrillex-style whu-whu-whu-whump-whump bass lines and some overproduced Zelda remixes that my friend tried to win me over with. I don't legitimately know what qualifies something as dubstep (which is fine because music is overclassified), but what I've heard has been pretty terrible