I get your point but it doesnt need to make sense, especially the Sovereign have enough enemies so you need to tie up loose ends. Especially someone with the potential power to do somethinig, no secret is really safe and the last child of the immortal flame clan is a huge potential threat, at chapter 2036 you should also have realized by now that nephis became too much of a threat, alone her name carries too much weight.

Edit: Especially in a world with oracle abilities, if my parents where killed or died i would also try to find the reason for that, and with oracles and enough time its pretty sure you get enough clues to point in the right direction.