In the Divine City, generally, there is no big rule fighting, but as long as it doesn't lead to fatalities, small-scale conflicts are not overly scrutinized, provided they don't escalate.
In an environment like the Divine Realm, the living beings all have strong abilities, and being combative has long become a trend. In such a scenario, expecting a Deity entering the Divine City to play nice was never a possibility.
Thus, at first, the Deity might have thought Zhou Tian was penniless and didn't want him entering their shop. But after Zhou Tian took action against them, the Deity felt slighted and wanted to teach Zhou Tian a good lesson.
Judging by the Divine Land Strength the Deity summoned, if they were determined to give Zhou Tian a hard time, Zhou Tian might not be able to cope.