It is not a matter of being humble for him to claim that he might not be the strongest. He hasn't proven his strength to compare himself to them.
He can also fight the Orc Bandits right now and defeat them to claim his position as the strongest god, but he clearly doesn't plan to do that. He plans to fight them together with the tens of thousands of other gods. He is smart to plan that, but Legion is no slouch either.
Legion-1 shrugged and said, "We can be patient. We will follow your rules for now. But we will attack any divine calamity we want. No one can stop us from doing that."
They didn't give him the opportunity to use the gods against them. They gave up on hunting the gods and switched to hunting divine calamities. This way the gods would have a lesser reason to unite and gang up on them.
