Before Hao Ren arrived in Aerym, he had promised the moon. However, when he was finally before Hilda, he was a little embarrassed to ask her for the favor—he came not for rent, but troops.
Even if everything went well, and the armed escorts were not presented with any danger (very few races from Y'zaks' homeland were capable in air combat, while space wars were rare), it was too much to ask people to risk their lives in a different world. Hao Ren had also seen the situation in Aerym: it was a crucial moment for the elves to rebuild their homes as they were trying to adapt to an unfamiliar planet. During this critical period, how many men could they set aside to run his errand?
Before Hao Ren came, he thought he had a billion tenants. But only then did it dawn on him that the one billion tenants were actually refugees.