Even if he was fully recovered, breeding isn't exactly a walk in the park for these guys. Nipping and chasing are part of the courtship to some degree, and this combined with his recent injuries might stress him to the point he could get sick. Not to mention that some betta girls can be meaner than the males! There's no guarantee that any given pair will be compatible in any case. Bettas are solitary critters by nature, and as soon as the girlie drops her eggs, the male will chase her out, even kill her as she's then viewed as a threat to his babies.
Not to mention the cost of breeding! You need a spawn tank of at least 10g, a filter of some kind, food for the fry, places to put the fry once they can no longer be housed together... breeding bettas isn't a lucrative business :/
Bubblenests mean he's feeling better, which is good! Don't compromise his recovery by overwhelming him with a girl! Best wishes for his speedy healing
