He is incomplete, but If he can defeat his avatars, he will regain control them and recover some of his power.
If he can defeat this tiger avatar, he will gain control over three avatars, not one because this tiger has already defeated two other avatars, so it is a package deal.
If he can take this one for three avatar and combine their power with the one avatar he already controls, he would gain control over five avatars out of the total nine.
Control over five avatars will put him ahead of the halfway point in his quest to regain total control of his power. This why he is hoping to take advantage of the fight, not help his avatar.
There really was no other way around his current situation. He had to make that deal with his divine flesh and couldn't fool them because they had his memories after awakening.
Because of his memories, the deal had to be fair. The deal also had to enticing to his divine flesh or they wouldn't have accepted it.
