I think it depends on whether or not you look at it as a martial art. I don't see why it couldn't be, yet most people I've seen don't consider it as such.
Many people don't think that a gun "counts" because it's "point and shoot", "doesn't take skill", and so forth. Course, most of us know different, but still don't consider it an art form.
Considering martial arts throughout history is largely based on the technology of the time (with regards to weaponry) I don't see why that should suddenly just stop after firearms became widespread. Rather, I would have thought it would adapt and a martial art would incorporate it.