Actually, it's not accurate to say that Green Lotus Temple wanted to gamble; in truth, Green Lotus Temple had no desire to gamble.
According to Taoist Yiyang's original intention, it was natural for Moon Wheel Sect to directly order the Zhou Family to withdraw from Jiufeng Ridge and forbid them from developing any influence within Lanzhou's borders in the future.
He didn't harbor any unrealistic hope that Moon Wheel Sect would entirely ignore the Zhou Family, allowing Green Lotus Temple to annihilate them.
However, Baiyue True Person evaded the issue entirely, claiming that the Zhou Family was a meritorious clan that had been rooted in Jiufeng Ridge for hundreds of years, unwilling to issue a forcible command for them to vacate Jiufeng Ridge.
After much back-and-forth between the two sides, Taoist Yiyang had discerned Baiyue True Person's bottom line and proactively proposed a dueling resolution, offering both sides a way to de-escalate the situation.