That's exactly what the parent comment said, since C is an imperative programming language:
> The genuine core feature of FP is the separation of data and methods, that stands in contrast not to imperative programming but object oriented programming, whose core feature is fusion of data and methods
Yes, the original comment posits that functional programming and imperative programming are the same thing, but that does not address the practical concerns of the parent. The harsh reality is that we have both "functional programming" and "imperative programming" terms with an intent for them to have different meanings.
Let's accept temporarily that functional programming and imperative programming are, indeed, the same thing. But now you have two terms with the same meaning still wanting to mean something different. A conflict in need of resolve. So, from this point forward what can we say that makes them different?
A trait I often see in languages that are considered functional, and not found in C, is the closure. Its purpose is to bind data with functions. That suggests to me that, as we seek a division in meaning, separation of data and functions is better left for the imperative definition rather than the functional definition.
Perhaps functional programming is best described as the intersection of imperative programming with "OO" programming? That seems to be the view the original commenter ends up taking in subsequent comments.
> The genuine core feature of FP is the separation of data and methods, that stands in contrast not to imperative programming but object oriented programming, whose core feature is fusion of data and methods