Prince Ji Yanting of Wu is very young; he is the youngest of his siblings, just turning twenty this year. Moreover, his fief is rather lackluster, situated in Jiangnan Province.
Truth be told, Su Xin had never heard of a royal member named Prince of Wu during his time in Jiangnan Province; hence, one could imagine how insignificant this prince was.
Jiangnan Province was essentially under the control of the Xiao Family before Su Xin arrived, making it impossible for Ji Yanting to expand his influence.
However, after the Crown Prince was deposed, Jiangnan Province was split between Su Xin and the Xiao Family, leaving no room for Ji Yanting to assert himself.
Initially, Ji Yanting had given up, resigning himself to a lifetime of idle princedom. So, when the Xiao Family proposed to support him as the leader of Great Zhou, Ji Yanting promptly refused.