Hey, I don't support genocide in real life, but let's be realistic, the Second Prince killed everyone, including the people in Aunt's house in the first life. It's very likely he'll get rid of all the Angenas again, even for certainty and future security, besides them being criminals. And we're talking about nobility and royalty, conflicts and purges of noble houses were normal in the setting that inspired the work.
Genocide would only be justifiable in real life in the case of "Total War". Total War is a war of extermination in which the losing side loses everything. It's a matter of survival. For example, if major powers decided to go to war and escalate to a nuclear level, one would be decimated first, and the other would gain the right to continue existing (full of the consequences of such a conflict).

I want the queen stripped and beheaded, and the extinction and massacre of all the Angenas. My dream is purge and genocide.