Saleen definitely would not have acted right away. He needed to wait for the situation to stabilize. Furthermore, he had a suppressed Heretic God to deal with. He intended to use that god to train his lightning skills further. If he were to only be able to rely on equipment to cast lightning skills, taking out the Lord of Glory would have been more difficult.
It was also quite a pain that the Lord of Glory had left so many doubles behind, and leaving any one of them alive would invite trouble.
Killing the Lord of Glory was just the start. Saleen intended to wipe out all god creatures in the divine kingdom. That was not something that could be done in just a day or two. Such a genocide would probably require decades to see through.
