The towering flower at the Middle Stage of the dao Seed Realm wasn't strong enough to pose any real threat, but it had become strong enough to resist his control to some extent. Making manipulation of it using the Dao of Corruption difficult. Killing it wasn't really an option either, as it had already merged with the corrupted terrain that covered a large section of the mountain range by now.
Not that it was impossible, just that it would give the guardian demon beast an opportunity to recover its strength, and he wasn't too worried about a single tentacle flower at the Middel Stage of the Dao Seed Realm. Even if it broke through to the Late or Peak Stage of the Dao Seed Realm, it would at most free itself from the control it was under and turn into a spectator.
