Lucifer understood just what kind of risk he was facing. He was being asked to help a potential enemy become stronger.
'Is this why I supposedly killed her? That doesn't make sense either. Even though she wants to get stronger, that shouldn't be enough for me to kill her in the future. There's something that still doesn't make sense.'
Even if he wanted to kill her like that, why would he do so in a way that makes everyone know that he was behind it? That's what didn't make sense to him. If he really wanted to make the entire Star Alliance turn against him, he could've done that after he was confident enough that he could wipe the Star Alliance completely.
Moreover, in that case, why would he be running from the Star Alliance? Currently, he believed he was already strong enough to face a Star Alliance General after he regained the strength from his other self. Then why was he running away from Star Alliance?