Nailisi was not willing to let this happen since she didn't want the imps and demonic spirits she had painstakingly summoned to become the Weapon's Spirit's subordinates. They were originally all demons who were loyal to her.
That being said, there was no way she could oppose Saleen's request. This matter would be extremely helpful in increasing his combat prowess.
Saleen needed to take the lead with Holy Rock City and assume power in Alchemy City. It was important for people to know that there was still a powerful bone dragon stationed in Alchemy City. Once the bone dragon acclimatized itself to the rules of the Myers Continent, or if the rank restriction there was relaxed, it might be able to leave after releasing its power, expanding its nest, and even releasing death-spirit descendants.
What a terrifying thought. Wherever the bone dragon passed, living creatures would be turned into death spirits. What a disastrous scene.