The fact that WAZA accepted JAZA zoos w/drive-caught dolphins in the first place is indisputable evidence of their support of animal cruelty. (I'm surprised there isn't a separate thread about this development. Maybe I missed it.)
Whether or not WAZA can encourage or discourage animal cruelty (or "force a zoo to do something") should not be an argument. By accepting certain members, they accept and normalize any practices that take place at those member's facilities. By refusing applicants or rejecting members which have proved themselves to be subpar, WAZA publicly shames them and calls attention to concerns at such substandard facilities.
In addition, WAZA defines its own reputation, goals, and priorities based on their membership. By excluding certain institutions, WAZA can develop a better reputation. WAZA's recent actions of suspending JAZA facilities and calling attention to the Surabaya Zoo's infractions are certainly beneficial for their reputation and demonstrate WAZA's principles. As they say, You have to put your money where your mouth is.
I look forward to seeing WAZA evolve and hope to see the organization take more initiative in solving zoo/aquarium issues so that the industry can reach its potential for education & conservation. The suspension of JAZA for their practices is some of the greatest news I've heard in a awhile.