I somehow or other guessed it based on those short words.
The Supard Race of that time would attack enemies and allies alike, without discretion, that entered their sight so to speak.
Most likely, he killed some people from the region Badigadi ruled over as well.
No matter how little he pays attention to the land he rules as a Demon King, he's still a ruler.
If your own territory has been attacked there's no way you can overlook it.