I am not doubting ZWJ's ability in memory and understanding of martial arts. But I just don't think that encompasses enough aspects of intelligence to qualify him.
I quite like this definition.
"Intelligence (also called intellect) is an umbrella term used to describe a property of the mind that encompasses many related abilities, such as the capacities to reason, to plan, to solve problems, to think abstractly, to comprehend ideas, to use language, and to learn."
ZWJ covers maybe 2 of those aspects. There are numerous characters who covers more and to a greater degree. So I don't understand why ZWJ was singled out. Characters like Zhao Min and Huang Rong just smashes ZWJ in most aspects of "intelligence". Check out Yideng.