It would be a huge hassle if Atlas had to leave this floating island. This place suited his needs better than anywhere else, both for his evolution and for his hunting. However, with the situation between him and the other lord already growing more heated, this was clearly not going to end well.
On top of that, their numbers were overwhelming. That alone gave them every advantage to launch the first attack against Atlas, whose own force was so much smaller.
And of course, he was not arrogant enough to challenge a lord and an army of that size, even though he had complete confidence in the people under his command. Numbers never lied, and if even one of his people ended up getting hurt because of a conflict that could not be avoided, he would never forgive himself for letting it happen.
