Although at the end of the day what a dragon is is rather arbitrary, especially if we draw on the various things that have been called a dragon instead of sticking to one version. But at the end of the day Borys is a big lizard with magic powers, even if he's not a 'true dragon' he's a dragon in all practical ways.
There's a bit more merit to 'Borys isn't a dragon' than to the 'only monks are martial artists' idea. But at this point we're getting into Dark Sun Magic/Biology technicalities that maybe one or two people care about in universe. At this point it's easier to fall back on descriptivism: people say it's a dragon, therefore it's a dragon.