Most importantly, the Ou Yang family couldn't allow Bao Hwa to grow anymore. If Bao Hwa really had swallowed Xi Empire, the Ou Yang family would have been their next target. That woman, Lin Jing, was too ambitious and would stop at nothing to expand her empire; she would not accept a life of normalcy. Therefore, after she took down Xi Empire, she would have gone after the Ou Yang family. Therefore, working together with Xi Empire was Ou Yang Qin's way of saving himself as well.
The result showed that he had chosen wisely. Thankfully he had decided to personally attend the showcase too because he was given a glimpse of Lin Jing's true personality. This Lin Jing would definitely not let the Ou Yang family be if she had the chance to take them down.