Daybreak's 'Boss' was actually quite predictable.
Among all the major organizations, Daybreak was the only one that completely disregarded the lives of ordinary people.
Even Moonlight might occasionally care about face, put on an act, but Daybreak had no such concerns; their reputation was already in tatters, so they had no need to worry about it anymore.
Moreover, judging by the 'Boss's' way of doing things in Alano, he was the type of person who wouldn't hesitate to use any means necessary to achieve his goals, which probably made him one of the more extreme members within Daybreak.
From his perspective, there was no need to consider the problems of the civilians in Eren, not to mention the city of Eren itself.
So, it was highly likely that he would choose to collaborate with the Primitive Church that worshipped the Evil God to go against 'Hao Yi'.
