That's exactly it though, if the client had an issue, don't wait 180 days.
Don't agree to a term to turn right around and say nevermind. Consistency matters a lot. Unfortunately a lot of artists have to deal with people not knowing what they want, and it drives down the whole working order of trying to make art in this Fandom work.
I'm all for fairness and equality but we're messing with someone's work, an artist trying to make a living from their art work is just as valid if not more in this case, you cannot argue ONLY the one side.