Board Thread:New on Hunterpedia/@comment-2405:4800:5A9F:1B52:A0BC:4D5A:E332:9996-20180814043320/@comment-48285-20180816053828

I agree: no. Unless it's confirmed in later chapters that Hisoka actually did propose to Illumi by hiring the Zoldyck to kill him, then we can only assume it was Hisoka being Hisoka. That is, not serious.