You're entirely misunderstanding me and the quote, as they both agree and align with what you're saying completely.
Again, the quote is not about avoiding or ignoring valid logical discourse, criticism, hypotheses, or any other logically coherent verbalization. The quote says that if the words are ambiguous, don't use them in logical arguments. Meaningless here does not mean hypothetical or conjectural or wrong, but simply ill-defined. This interpretation leaves plenty of room for everything you have described and are afraid would be criticized by the quote.
So, to get back to why I brought it up: creativity is an ill-defined concept in the context of logical reasoning, and so should not be used in logical reasoning as if it was an attribute that we can empirically or theoretically judge any entity to be in possession of.
This is why all replies to the above comment get lost in semantics: what is creativity? This is ill-defined, and hence based on your personal preference you may arrive freely at any conclusion you wish. Hence using the word "creativity" during a logical argument or truthful statement is guaranteed to produce conflict when multiple interpreters are present. Multiple logical interpreters can never be in conflict about purely logical reasoning, this is why we can have math.
Again, this is NOT saying that anything is unknowable, it is simply saying that whatever creativity is, or is composed of, is not clearly defined. This means it cannot be knowable or unknowable until it is clearly defined, and specifically only if done so in a rigorous enough definition to use it during reasoning.
To get back to your last point: doing what I described above is specifically to further the progress of our understanding of the universe, and specifically to attain new knowledge and understanding, because it cuts down on the discourse that does not contribute to that goal. It's the difference between arguing about whether machines have creativity and building DALL-E.