That would ahve to depend on Chao. Phoenix is incredibly eccentric and whimsical. She can lend her power to Chao, or not. She CAN take note of it, but she wouldn't per se, actually come out herself to deal with it. After all, she does plan to burn the universe if Chao fails, so Tsuki's dark side would be more an amusement and oddity to distract her, rather than an actual serious interest.
CHAO on the other hand, that is a different story.
You'll have to run along the situation when we get to it.
Not skewed. Her view is one of a higher being. To her, heartless, humans, dogs, cats, bacteria, trees... Everything has the same value and are all highly valued to her. She plays no favourite. While she has been using a human host at times to keep the universe in order (along with other dieties), it doesnt give them special privileges. To her, the heartless situation has gotten to the point where the human cannot contain it and since the humans were the first and last line defense against them, Phoenix has decided to take the purge route, where she burns the universe asunder and have it reborn (ala phoenix).
However, she has put this plan on hiatus, giving the group a chance. The enroachment isnt so straight forward as evil overtaking Chao's body. It is more complex and story driven than that.