The big thing here is that the Aul incinerator is GIVING tiles, not removing them! Planet quality goes up after it's construction.
Also, a strange bug I encountered: I got the dread lords mega event, and they decided to take over one of MY planets instead of an empty one. The result... my planet was overwritten, the planet and star were renamed to Amalga and all the improvements were written over with industrial sectors. However, my ships remained in orbit, yet I couldn't deorbit them! When I brought in my transport to end their "menace" I was actually incapable of invading until I went to the lease screen and manually scraped the fighters.
I'll admit, though, once I wiped out the dread lords, that was a REALLY nice planet to stick an Aul incinerator.