Why Simp?

I just can't understand Simp. "I can't just go after the earth with them around. There's only one solution, Wise. I need them gone". WHY? Does anyone even understood what she meant by that? Honestly, it feels like a very strange writing choice. Yeah, Rogue planets has obvious secrets from our planets. But wanting them gone makes zero sense whatsoever. Solar system planets had literally no suspicion about the Rogue Kingdom at all. Why she needs them gone and bringing millions of planets each (I know that was just an excuse for them to be gone)? Why, why, why? Especially WHEN THEY HAVE ONE PLANET FROM SOLAR SYSTEM WHO'S WORKING TO THEM (Planet X). I can't take "I can't just go after the earth with them around." statement. It feels so illogical.